Super-Earth Detected in Habitable Zone of Nearby Star

February 2, 2012

Santa Cruz, CA—An international team of scientists has discovered a potentially habitable super-Earth orbiting a nearby star. With an orbital period of about 28 days and a minimum mass 4.5 times that of the Earth, the planet orbits within the star’s “habitable zone,” where temperatures are neither too hot nor too cold for liquid water to exist on the planet’s surface. The researchers found evidence of at least one and possibly two or three additional planets orbiting the star, which is about 22 light years from Earth.

The researchers used public data from the European Southern Observatory and analyzed it with a novel data-analysis method. They also incorporated new measurements from the W. M. Keck Observatory’s High Resolution Echelle Spectrograph (HiRES) and the new Carnegie Planet Finder Spectrograph at the Magellan II Telescope. Their planet-finding technique involved measuring the small wobbles in a star’s motion caused by the gravitational tug of a planet.

The team includes UC Santa Cruz astronomers Steven Vogt and Eugenio Rivera and was led by Guillem Anglada-Escudé and Paul Butler of the Carnegie Institution for Science. Their work will be published by Astrophysical Journal Letters, and the manuscript will be posted online at arxiv.org/archive/astro-ph.

The host star is a member of a triple-star system and has a different makeup than our sun, with a much lower abundance of elements heavier than helium, such as iron, carbon, and silicon. This discovery indicates that potentially habitable planets can occur in a greater variety of environments than previously believed.

The host star, called GJ 667C, is an M-class dwarf star. The other two stars in the triple-star system (GJ 667AB) are a pair of orange K dwarfs, with a concentration of heavy elements only 25 percent that of our sun’s. Such elements are the building blocks of terrestrial planets, so it was thought to be less likely for metal-depleted star systems to have an abundance of low-mass planets.

“This was expected to be a rather unlikely star to host planets. Yet there they are, around a very nearby, metal-poor example of the most common type of star in our galaxy,” said Vogt, a professor of astronomy and astrophysics at UC Santa Cruz. “The detection of this planet, this nearby and this soon, implies that our galaxy must be teeming with billions of potentially habitable rocky planets.”

GJ 667C had previously been observed to have a super-Earth (GJ 667Cb) with a period of 7.2 days, although this finding was never published. This planet orbits so close to the star that it would be too hot for liquid water. The new study started with the aim of obtaining the orbital parameters of this super-Earth.

But in addition to this first candidate, the research team found the clear signal of a new planet (GJ 667Cc) with an orbital period of 28.15 days and a minimum mass of 4.5 times that of Earth. The new planet receives 90 percent of the light that Earth receives. However, because most of its incoming light is in the infrared, a higher percentage of this incoming energy should be absorbed by the planet. When both these effects are taken into account, the planet is expected to absorb about the same amount of energy from its star that the Earth absorbs from the sun.

“This planet is the new best candidate to support liquid water and, perhaps, life as we know it,” Anglada-Escudé said.

The team found that the system might also contain a gas-giant planet and an additional super-Earth with an orbital period of 75 days. However, further observations are needed to confirm these two possibilities.

“With the advent of a new generation of instruments, researchers will be able to survey many M dwarf stars for similar planets and eventually look for spectroscopic signatures of life in one of these worlds,” said Anglada-Escudé, who was with Carnegie when he conducted the research, but has since moved on to the University of Gottingen.

In addition to Anglada-Escudé, Butler, Vogt, and Rivera, the coauthors include Jeffrey Crane, Stephen Shectman, and Ian Thompson at Carnegie; Pamela Arriagada and Dante Minniti of Pontificia Universidad Catolica de Chile; Nader Haghighipour of the University of Hawaii-Monoa; Brad Carter of University of Southern Queensland; C. G. Tinney, Robert Wittenmyer, and Jeremy Bailey of the University of New South Wales; Simon J. O’Toole of the Australian Astronomical Observatory; Hugh Jones of the University of Hertfordshire; and James Jenkins of the Universidad de Chile, Camino El Observatorio.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

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This press release was adapted from one originally issued by U.C. Santa Cruz.

Keck Observatory Astronomer Wins Top Award

January 20, 2012

A Keck Observatory astronomer who led the way to the discovery of a super-massive black hole at the center of our galaxy has been recognized this week with the 2012 Crafoord Prize in Astronomy, an award almost as prestigious for astronomers as a Nobel Prize.

“This is a big one. I’m thrilled,” said Andrea Ghez of the University of California at Los Angeles. For more than 16 years Ghez and her team have been pushing the frontiers of high-resolution imaging technologies with the twin 10-meter Keck telescopes in order to explore the center of the Milky Way. By tracking the rapid, small-scale orbits of stars at the Galactic Center, they discovered the presence of a source of tremendous gravity – the best evidence yet that a supermassive black hole exists there. The reality of such an object confronts and challenges our knowledge of fundamental physics.

Ghez , who holds UCLA’s Lauren B. Leichtman & Arthur E. Levine Chair in Astrophysics and heads UCLA’s Galactic Center Group, will be sharing the prize, and its 4 million Swedish Krona or $600,000 award, with Reinhard Genzel, scientific director of Max-Planck-Institute for Extraterrestrial Physics in Garching, Germany. Genzel leads a group that has long worked independently to track the same stars at the Galactic Center.

“This year´s Crafoord Prize Laureates have found the most reliable evidence to date that super-massive black holes really exist,” reads a Jan. 19 release from the Royal Swedish Academy of Sciences. “For decades Reinhard Genzel and Andrea Ghez, with their research teams, have tracked stars around the center of the Milky Way galaxy. Separately, they both arrived at the same conclusion: in our home galaxy resides a giant black hole, called Sagittarius A.”

Ghez, born in New York City and raised in Chicago, started the project in 1995, when she was a fresh new assistant professor at UCLA, looking for a project that would make good use of her talents in high-resolution imaging.

“I had no idea that this project would lead to such recognition” Ghez laughed. “I was a new assistant professor and I was just looking for tenure. It was my very first Keck proposal.”

Her proposal was accepted and she went to work showing how a technique called speckle imaging could be used to dramatically sharpen images using what was at the time the world’s only 10-meter optical-infrared telescope: Keck I. Speckle imaging corrects for the blurring effects of the earth’s atmosphere in processing of images after they have been captured by the telescopes’ instruments. These allowed the first diffraction-limited images – that is, images that are limited by a telescope’s power rather than the Earth’s turbulent atmosphere – to be produced with these large ground-based telescopes.

“I wanted to show that speckle worked at Keck,” Ghez said. It did and it produced the first images that had the full resolving power of the Keck telescope. But that was just a start. By 1999 the Keck II telescope was also operating and had become the first large telescope in the world to employ adaptive optics, a technology that cancels out distortions in starlight created by turbulence in Earth’s atmosphere. That sharpened the images of the Galactic Center ten-fold and allowed diffraction-limited spectroscopic measurements to be made for the first time.

“It’s been like riding this incredible wave of technology,” Ghez said. “Since 1995 we have spent time at the telescopes every summer working on this. I had no idea what a rich project I was getting into at first. While the initial question was ‘is there a supermassive black hole at the center of our galaxy’, we have uncovered so many unexpected phenomena and technology has moved so fast that we created more questions than we answered”

“This research was possible thanks to the W. M. Keck Observatory, which houses the two largest telescopes in the world,” said Ghez. “They have enabled us to achieve the tremendous progress that we have made in correcting the distorting effects of the Earth’s atmosphere with high-angular resolution imaging. The most recent technology of adaptive optics is now opening up new horizons and allowing us to learn even more about this black hole at the center of our galaxy – how it was formed, how it grows and how to correctly describe the properties of space and time in the vicinity of such an exotic object.”

Another thing that helped the research was the competition between the two research teams, Ghez said.

“There’s nothing like competition to spur you on,” Ghez said. “It’s been a very collegial, constructive competition.”

And all that competition spins back around to drive the technology.

“Andrea has been a passionate and tireless user of the Keck telescopes and our high-angular-resolution imaging capabilities to study the Galactic Center and its super-massive black hole,” said Keck Observatory director Taft Armandroff. “I have no doubt that our adaptive optics capabilities are stronger and more tailored to address astrophysical questions by virtue of Andrea’s involvement and that of her team.”

The Crafoord Prize is an annual award that rotates between the disciplines of astronomy, mathematics, geosciences, biosciences and arthritis research. This year’s honorees came from mathematics and astronomy, fields last recognized in 2008. The prize will be presented by the King of Sweden, at an award ceremony held on May 15, 2012. Andrea Ghez will be the first woman to be awarded this prize in any field in its 30-year history.

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Most Distant Dwarf Galaxy Detected

January 18, 2012

Kamuela, HI—Scientists have long struggled to detect the dim dwarf galaxies that orbit our own galaxy. So it came as a surprise on Jan. 18 when a team of astronomers using Keck II telescope’s adaptive optics has announced the discovery of a dwarf galaxy halfway across the universe.

The new dwarf galaxy found by MIT’s Dr. Simona Vegetti and colleagues is a satellite of an elliptical galaxy almost 10 billion light-years away from Earth. The team detected it by studying how the massive elliptical galaxy, called JVAS B1938 + 666, serves as a gravitational lens for light from an even more distant galaxy directly behind it. Their discovery was published in the Jan. 18 online edition of the journal Nature.

Like all supermassive elliptical galaxies, JVAS B1938 + 666’s gravity can deflect light passing by it. Often the light from a background galaxy gets deformed into an arc around the lens galaxy, and sometimes what’s called an Einstein ring. In this case, the ring is formed mainly by two lensed images of the background galaxy. The size, shape and brightness of the Einstein ring depends on the distribution of mass throughout the foreground lensing galaxy.

Vegetti and her team obtained extra sharp near-infrared image of JVAS B1938 + 666 by using the 10-meter Keck II telescope and its adaptive optics system, which corrects for the blurring effects of Earth’s atmosphere, and provides stunningly sharp images. With these data, they neatly determined the mass distribution of JVAS B1938 + 666 as well as the shape and brightness of the background galaxy.

The researchers used a sophisticated numerical technique to derive a model of the lens galaxy’s mass, as well as to map any excess lens mass that could not be accounted for by the galaxy. What they found was an excess mass near the Einstein ring that they attributed to the presence of a satellite, or “dwarf,” galaxy. Vegetti’s team also used a separate analytical model to test the detected excess mass. They found that a satellite galaxy is indeed required to explain the data.

“This satellite galaxy is exciting because it was detected in the excess-mass map despite its low mass,” commented Robert Schmidt of the Center for Astronomy at Heidelberg University, in a related Nature article. “A natural question to ask is whether the satellite galaxy can be observed directly rather than by its gravitational effect on the shape of a background object. With current instrumentation, the answer is no. The object is simply too distant to be imaged directly. But the message here is that it is possible to spot these elusive objects around distant lens galaxies without knowing where to look for them.”

Galaxies like our own are believed to form over billions of years through the merging of many smaller galaxies. So it’s expected that there should be many smaller dwarf galaxies buzzing around the Milky Way. However, very few of these tiny relic galaxies have been observed which has led astronomers to conclude that many of them must have very few stars or possibly may be made almost exclusively of dark matter.

Scientists theorize the existence of dark matter to explain observations that suggest there is far more mass in the universe than can be seen. However, because the particles that make up dark matter do not absorb or emit light, they have so far proven impossible to detect and identify. Computer modeling suggests that the Milky Way should have about 10,000 satellite dwarf galaxies, but only 30 have been observed.

“It could be that many of the satellite galaxies are made of dark matter, making them elusive to detect, or there may be a problem with the way we think galaxies form”, says Vegetti.

In the new study, Vegetti worked with Prof. Leon Koopmans of the University of Groningen, Netherlands; Dr. David Lagattuta and Prof. Christopher Fassnacht of the University of California at Davis; Dr. Matthew Auger of the University of California at Santa Barbara; and Dr. John McKean of the Netherlands Institute for Radio Astronomy.

“The existence of this low-mass dark galaxy is just within the bounds we expect if the Universe is composed of dark matter which has a low temperature. However, further dark satellites will need to be found to confirm this conclusion,” says Vegetti.

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Adapted from a MIT press release.

For more information please visit
http://web.mit.edu/physics/people/pappalardo/vegetti_simona.html
http://web.mit.edu/physics/index.html
http://web.mit.edu/newsoffice/2009/dark-matter-091709.html

Smallest Solar System Found

January 9, 2012

KAMUELA, HI – For years the search for exoplanets has largely been like Gulliver’s visit to Brobdingnag: colossal systems of giant gas planets orbiting mammoth stars. But astronomers have finally landed on the shores of Lilliput. They have found a tiny star with three puny planets, each smaller than Earth, zooming around it.

The three small exoplanets orbit a star called KOI-961. Their radii are calculated to be 78, 73 and 57 percent that of Earth. The sizes of the planets were worked out by Kepler Telescope observations that measured the dimming of the star KOI-961 as each planet passes in front of it. This plus crucial information about the star from Keck and Palomar telescopes enabled researchers to determine the sizes of the planets.

Although the masses of the three planets are unknown, they are suspected of being rocky, like Earth, Venus, Mars and Mercury. But they orbit too close to their star to be in the habitable zone where liquid water could exist. The three planets take less than two days to orbit around KOI-961, which is a red dwarf with a diameter one-sixth that of our sun, making it just 70 percent bigger than Jupiter.

“This is the tiniest solar system found so far,” said John Johnson, the principal investigator of the research from NASA’s Exoplanet Science Institute at the California Institute of Technology in Pasadena. “It’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy.”

Red dwarfs are the most common kind of star in our Milky Way galaxy. The discovery of three rocky planets around one red dwarf suggests that the galaxy could be teeming with similar rocky planets.

“These types of systems could be very common in the universe,” said Phil Muirhead, lead author of the new study from the California Institute of Technology in Pasadena. “This is a really exciting time for planet hunters.”

Muirhead’s team used data publicly released by the Kepler mission, along with follow-up observations from the Palomar Observatory, near San Diego, and the Keck Observatory on Mauna Kea in Hawaii.

The researchers determined the sizes of the three planets (called KOI-961.01, KOI-961.02 and KOI-961.03) with the help of a well-studied twin star to KOI-961, called Barnard’s Star. Spectra of both stars obtained by the Keck I telescope’s High Resolution Echelle Spectrometer (HIRES) show the stars to be almost identical. By matching KOI-961 with Barnard’s Star in this way, they could then work out how big the planets must be to have caused the observed dips in starlight.

In addition to the telescope observations, the team used modeling techniques to confirm the planet discoveries. Their measurements dramatically reduced the sizes of the planets from what was originally estimated from Kepler measurements.

“Astronomers are just beginning to confirm the thousands of planet candidates uncovered by Kepler so far,” said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Finding one as small as Mars is amazing, and hints that there may be a bounty of rocky planets all around us.”

The Kepler Mission is a space telescope launched by NASA in 2009 that measures light from 150,000 stars. Scientists working with Kepler data look for changes in stellar brightness that suggest a transit, or a planet passing in front of a star. They use measurements of the star’s luminosity to determine whether the planet is in a “habitable zone,” an area where the planet would be stable and conditions hospitable to life could exist.

Keck & Subaru Telescopes Find Rare Galaxy at Dawn of Time

December 21, 2011

Synopsis:

• The galaxy GN-108036 is one of the most distant objects ever found in the universe.
• Galaxies like GN-108036 may be responsible for ending the universe’s early “Dark Age.”
• The Keck II Telescope was used to confirm the distance and age of the galaxy after it was spotted with the Subaru Telescope.

Kamuela, HI – Astronomers have spotted one of the most distant galaxies known, churning out stars at a shockingly high rate. The blob-like galaxy, called GN-108036, is located 12.9 billion light-years away from Earth, and is the most luminous galaxy known at that great distance.

The galaxy was first identified by the Subaru telescope and its extreme distance was then carefully confirmed with the Keck II telescope and its DEIMOS instrument (Deep Extragalactic Multi-Object Spectrograph). Both observatories are located on the summit of Mauna Kea, Hawaii. NASA’s Spitzer and Hubble space telescopes were used to measure the galaxy’s high star production rate, equivalent to about 100 suns per year. For comparison, our Milky Way galaxy is about five times larger and a hundred times more massive than GN-108036, but makes new stars roughly 30 times more slowly.

“We’re really surprised to know that GN-108036 is quite luminous in ultraviolet and harbors a powerful star formation,” said astronomer Yoshiaki Ono of the University of Tokyo, Japan. “We had never seen such a vigorously star-forming galaxy at a comparable distance until the discovery of GN-108036.” Ono is the lead author on a paper on the results that is accepted for publication in The Astrophysical Journal. The principal investigator is Masami Ouchi, also at the University of Tokyo.

“The discovery is surprising because previous surveys had not found galaxies this bright that early in the history of the universe,” agreed Mark Dickinson of the National Optical Astronomy Observatory in Tucson. “Perhaps those surveys were just too small to find galaxies like GN-108036. It may be a special, rare object that we just happened to catch during an extreme burst of star formation.”

GN-108036 lies near the very beginning of time itself, a mere 750 million years after our universe was created in an explosive “big bang.” Its light has taken 12.9 billion years to reach us, so we are seeing it as it was in the very distant past.

Astronomers refer to the object’s distance by a number called its “redshift,” which relates to how much its light has stretched to longer, redder wavelengths due to the expansion of the universe. Objects with larger redshifts are farther away and are seen further back in time. GN-108036 has a redshift of 7.2, making it one of only a handful of galaxies have confirmed redshifts greater than 7. Only two others have been reported to be more distant than GN-108036.

During this epoch, as the universe expanded and cooled after its explosive start, hydrogen atoms permeating the cosmos formed a thick fog that was opaque to ultraviolet light. This period, before the first stars and galaxies had formed and illuminated the universe, was known as the “dark ages.” The dark ages came to an end when light from the earliest galaxies burned through, or “ionized”, the opaque gas, causing it to become transparent. Galaxies similar to GN-108036 may have played an important role in this event. The question to be answered now is how many of these galaxies existed back then.

“The high rate of star formation found for GN-108036 implies that it was rapidly building up its mass some 750 million years after the Big Bang, when the universe was only five percent of its present age,” said Bahram Mobasher, a member of the team from the University of California, Riverside. “This was therefore a likely ancestor of massive and evolved galaxies seen today.”

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Kepler, Keck Telescopes Discover Earth-Size Exoplanets

December 20, 2011

NASA’s Kepler mission, aided by the Keck I Telescope, has discovered the first Earth-size planets orbiting a Sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet’s surface, but they are the smallest exoplanets ever confirmed around a star like our Sun.

The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1,000 light-years away in the constellation Lyra.

Kepler-20e orbits its parent star every 6.1 days and Kepler-20f every 19.6 days. These short orbital periods mean very hot, inhospitable worlds. Kepler-20f, at 800 degrees Fahrenheit (427 degrees Celsius), is similar to an average day on the planet Mercury. The surface temperature of Kepler-20e, at more than 1,400 degrees Fahrenheit (760 degrees Celsius), would melt glass.

“The primary goal of the Kepler mission is to find Earth-sized planets in the habitable zone,” said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of a new study published in the journal Nature. “This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them.”

The Kepler-20 system includes three other planets that are larger than Earth but smaller than Neptune. Kepler-20b, the closest planet, Kepler-20c, the third planet, and Kepler-20d, the fifth planet, orbit their star every 3.7, 10.9 and 77.6 days, respectively. All five planets have orbits lying roughly within Mercury’s orbit in our solar system. The host star belongs to the same G-type class as our Sun, although it is slightly smaller and cooler.

The system has an unexpected arrangement. In our solar system, small, rocky worlds orbit close to the Sun and large, gaseous worlds orbit farther out. In comparison, the planets of Kepler-20 are organized in alternating size: large, small, large, small and large.

Scientists are not certain how the system evolved, but they do not think the planets formed in their existing locations. They theorize the planets formed farther from their star and then migrated inward, likely through interactions with the disk of material from which they originated. This allowed the worlds to maintain their regular spacing despite alternating sizes.

The Kepler space telescope detects planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets crossing in front of, or transiting, their stars. The Kepler science team requires at least three transits to verify a signal as a planet.

The Kepler science team then turned to the Keck I Telescope and the Spitzer Space Telescope. The Keck I telescope’s HIRES instrument (High Resolution Echelle Spectrometer) was used to see if the star has a detectable wobble from the tug of the small planets. This is the way most of Kepler’s planet candidates are confirmed. In the case of Kepler-20e and Kepler-20f, no wobble was detected, which means the planets, despite being detected repeatedly transiting in front of the star are very small – in the Earth range – and their tug on their star is very small.

The star field Kepler observes in the constellations Cygnus and Lyra can be seen only from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

To validate Kepler-20e and Kepler-20f, astronomers used a computer program called Blender, which runs simulations to help rule out other astrophysical phenomena masquerading as a planet.

On Dec. 5, the team announced the discovery of Kepler-22b in the habitable zone of its parent star, a discovery that also involved Keck telescope data. It is likely to be too large to have a rocky surface. While Kepler-20e and Kepler-20f are Earth-size, they are too close to their parent star to have liquid water on the surface.

“In the cosmic game of hide and seek, finding planets with just the right size and just the right temperature seems only a matter of time,” said Natalie Batalha, Kepler deputy science team lead and professor of astronomy and physics at San Jose State University. “We are on the edge of our seats knowing that Kepler’s most anticipated discoveries are still to come.”

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Adapted from a NASA press release.

Keck Telescope Creator To Receive 2012 Franklin Medal

December 19, 2011

The Franklin Institute in Philadelphia has announced that Jerry Nelson, professor of astronomy and astrophysics at the University of California, Santa Cruz, will receive the 2012 Benjamin Franklin Medal in Electrical Engineering.

Nelson is internationally renowned as a developer of innovative designs for advanced telescopes. The Franklin Institute is honoring him “for his pioneering contributions to the development of segmented-mirror telescopes.”

The Franklin Institute awards are among the oldest and most prestigious comprehensive science awards in the world. Since 1824, the institute has honored excellence and achievement in science, engineering, and technology. Nelson will receive the Franklin Medal at an awards ceremony in Philadelphia in April.

Nelson played a central role in the design of the twin Keck Telescopes at the W. M. Keck Observatory in Hawaii, conceiving the revolutionary segmented design of the Kecks’ 10-meter primary mirrors. As founding director of the Center for Adaptive Optics, a National Science Foundation science and technology center headquartered at UC Santa Cruz, Nelson helped pioneer the use of adaptive optics for astronomy, enabling scientists to get sharp images from ground-based telescopes. He is now project scientist for the Thirty-Meter Telescope (TMT), which is currently in the design phase.

A member of the National Academy of Sciences, Nelson has received many awards for his achievements, including the 2010 Kavli Prize in Astrophysics from the Norwegian Academy of Science and Letters, the André Lallemand Prize of the French Academy of Sciences, and the American Astronomical Society’s Dannie Heineman Prize for Astrophysics. He earned a B.S. in physics from the California Institute of Technology and a Ph.D. in elementary particle physics from UC Berkeley. Nelson joined the faculty at UC Santa Cruz in 1994.

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The Franklin Institute’s mission is to inspire an understanding of and passion for science and technology learning. Through its awards, the institute seeks to broaden public awareness and encourage understanding of science and technology. Accordingly, the work of nominated individuals is evaluated on the basis of uncommon insight, skill, and creativity, as well as its ability to impact the future or have some public benefit.

More information about the Franklin Institute awards:
http://www.fi.edu/franklinawards/index.html

Adapted from a U.C. Santa Cruz press release by Tim Stephens

VIDEO: Oodles of Exoplanets

December 16, 2011

This is the video of a Dec. 8, 2011, Keck Astronomy Talk at the Kahilu Theatre in Waimea-Kamuela, Hawaii. The talk is entitled “Oodles of Exoplanets: The Search for Other Earths,” by Greg Laughlin, an astronomer at the University of California at Santa Cruz.

NOTE: There is an audio problem at the beginning of this video. It does not last throughout the video. Our apologies for the technical problem.

Astronomers Find New Clues to Supernova Origins

December 14, 2011

Synopsis:

Astronomers have taken a big step forward in identifying the unseen partners of stars that blow up and make the universe’s “standard candle” supernovas.
Observations by both Keck telescopes played key roles in the new discoveries.
These standard candles, Type Ia supernovas, were used to discover that the universe is expanding at an accelerating rate, which implies the existence of dark energy—a revelation that was awarded the Nobel Prize in Physics last week.

Berkeley – Discoveries announced this week about the summer’s historic Pinwheel Galaxy supernova are due, in part, to both Keck telescopes and their uniquely powerful instruments. Two papers in the Dec. 15 edition of the journal Nature shed unprecedented light on the details of the stellar explosion—which was the closest of its very important kind in decades.

The first role was played by the Keck II telescope which was used to precisely locate the August explosion, dubbed SN 2011fe. This was essential for finding the “progenitor” star that led to the explosion—or its companion star—in pre-explosion images of the Pinwheel galaxy.

University of California, Berkeley research astronomer Weidong Li pulled up images of the northern sky taken over the past nine years by the Hubble Space telescope in hopes of seeing the supernova’s progenitor star. Oddly enough, he found nothing. But Li’s initial disappointment quickly turned to excitement.

“We soon realized that the non-detection limit of the Hubble Space Telescope may be stringent enough to let us rule out some proposed progenitor systems,” he said.

To pinpoint the precise supernova location in the Hubble Space Telescope images, Li and his colleagues obtained a mosaic image of the field of SN 2011fe with the Near-Infrared Camera 2 (NIRC2) mounted behind the adaptive optics system on the Keck II telescope. The Keck adaptive optics image—which cancels out atmospheric distortions—was matched with Hubble Space Telescope/Advanced Camera for Surveys images, yielding a better-than-Hubble precision of 0.022 arc-seconds for the supernova position.

“Our paper is the first ever to exclude directly some of the major candidates for Type Ia supernovae,” said coauthor Joshua Bloom, a UC Berkeley astronomer. While the star that explodes to produce a Type Ia supernova is thought to be a white dwarf composed primarily of carbon and oxygen, the white dwarf presumably explodes because it pulls matter from a binary companion that to date has been a mystery.

Li and colleagues analyzed high-resolution Hubble data and calculated that the companion could not have been a red giant star, which typically are bloated and bright, or most types of helium stars, which also would have been visible.

This fits with theoretical modeling of the exploding white dwarf by the supernova’s discoverers: Peter Nugent, head of the Computational Cosmology Center at Lawrence Berkeley National Laboratory, and his colleagues. Nugent’s group used another observation from the Keck I that was gathered just hours after the exploding star was discovered. This was a high-resolution spectrum obtained with the HIRES spectrograph at the Keck I telescope. This spectrum, plus a low-resolution spectrum from the Kast spectrograph at the Lick 3-meter Shane telescope (Mt. Hamilton, California) allowed astronomers to estimate the time of explosion with high precision.

Nugent and his colleagues also published their conclusions in the Dec. 15 issue of Nature.

Together, the findings of Li’s and Nugents’s teams make astronomers confident that the companion was most likely either a normal star like the sun, a somewhat evolved star called a subgiant, or perhaps a white dwarf.

“The two papers suggest that a main-sequence star companion agrees with all the observed properties of the supernova progenitor luminosity limits and the evolution of the supernova,” said coauthor Saurabh Jha, an astronomer at Rutgers University.

Type Ia supernovae are bright and visible across huge cosmic distances, which allowed UC Berkeley’s Saul Perlmutter, his Nobel laureate colleagues and their teams to employ them as “standard candles” to measure the universe. In 1998, these studies revealed that the expansion of the universe is accelerating, now widely believed to require the presence of a mysterious “dark energy.”

“The discovery of the accelerating expansion of the Universe has revolutionized physics, and the repulsive dark energy may provide key clues to the long-sought quantum theory of gravity,” said UC Berkeley astronomer Alex Filippenko, who was a member of both of the teams that made the Nobel Prize-winning discovery. “But the actual origins of Type Ia supernovae have remained mysterious, and various aspects of the explosion are not well understood.”

“Our next step is to detect the surviving companion star, perhaps using the James Webb Space Telescope when it comes online. That will give us another opportunity to reveal more secrets about this supernova and ultimately help us understand the explosion physics of Type Ia supernovae, and possibly refine them as an even better cosmological distance ladder,” Li said.

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New Goldilocks Planet Detected

December 6, 2011

Washington, D.C.—The Keck I telescope has been used to establish the mass of a planet in the habitable zone around a star—that’s the region where liquid water could exist on a planet’s surface. The newly confirmed exoplanet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our Sun. The exoplanet is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like exoplanets.

Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation has proved very difficult. Two other small planets orbiting stars smaller and cooler than our Sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars than that of Earth.

“This is a major milestone on the road to finding Earth’s twin,” said Douglas Hudgins, scientist for NASA’s Kepler mission, which first detected the planet.

The Kepler spacecraft was launched in March of 2009 as a NASA Discovery Mission designed to search for exoplanets. The spacecraft has an 84-megapixel camera which stares continuously at a field of 150,000 stars in the constellations Cygnus and Lyra. Kepler discovers exoplanet candidates by measuring dips in the brightness stars to search for exoplanets that cross in front of, or “transit,” the stars. The process is similar to what occurs during a solar eclipse: in that case, our Moon temporarily blocks light from our Sun, but in this case the distant planet moves across the face of the distant star and causes a much smaller decrease in the amount of light we observe from the star. Kepler requires at least three transits to verify a signal as a exoplanet. Astronomers then turn to the Keck I telescope’s powerful HIRES spectrometer to determine the mass of the exoplanet candidates.

“Fortune smiled upon us with the detection of this planet,” said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. “The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season.”

Kepler-22b and its anonymous parent star are located 600 light-years away. While the planet is more massive than Earth, its orbit of 290 days around a Sun-like star resembles that of our world. The planet’s host star belongs to the same class as our Sun, called G-type, although it is slightly smaller and cooler.

Of the 54 habitable-zone planet candidates identified by the Dr. Borucki’s team in February 2011, Kepler-22b is the first to be confirmed. The discovery of this milestone will be published in a research paper to appear in The Astrophysical Journal.

Early in its mission, the Kepler satellite discovered many large planets in small orbits, which comprised the bulk of the planets reported in the February data release. Now that the science team has had time to acquire data over a period long enough to observe three transits of earthlike planets with longer orbital periods, their findings suggest that planets one to four times the size of Earth may be abundant in the galaxy.

Since Feburary 2011, the number of Earth-size planet candidates has doubled and the count of super-Earth-size candidates is now 40 percent higher than before.

The Kepler team has now revised its estimate of the number of habitable-zone planets to 48, down from 54 reported in Feburary. This decrease results from an updated definition of the “habitable zone” which now accounts for the warming effect of planetary atmospheres. This change moves the habitable zone further away from the star and, as a result, certain stars with shorter orbital periods are no longer classified as existing within the habitable zone.

“The tremendous growth in the number of Earth-size candidates tells us that we’re honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable,” said Natalie Batalha, Kepler deputy science team lead at San Jose State University in California. “The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods.”

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Adapted from a NASA press release.

Record Massive Black Holes Found Lurking in Monster Galaxies

December 5, 2011

BERKELEY—Astronomers using the Keck II telescope and other observatories have discovered the largest black holes to date—two monsters with masses equivalent to 10 billion Suns that are threatening to consume anything, even light, within a region five times the size of our solar system.

These black holes are at the centers of two galaxies more than 300 million light-years from Earth, and may be the dark remnants of some of the very bright galaxies, called quasars, that populated the early universe.

“In the early universe, there were lots of quasars or active galactic nuclei, and some were expected to be powered by black holes as big as 10 billion solar masses or more,” said Chung-Pei Ma, University of California, Berkeley, professor of astronomy. “These two new supermassive black holes are similar in mass to young quasars, and may be the missing link between quasars and the supermassive black holes we see today.”

Black holes are dense concentrations of matter that produce such strong gravitational fields that even light cannot escape. While exploding stars, called supernovas, can leave behind black holes the mass of a single star like the Sun, supermassive black holes have presumably grown from the merger of other black holes or by capturing huge numbers of stars and massive amounts of gas.

“These black holes may shed light on how black holes and their surrounding galaxies have nurtured each other since the early universe,” said UC Berkeley graduate student Nicholas McConnell, first author of a paper on the discovery being published in the Dec. 8 issue of the British journal Nature by McConnell, Ma and their colleagues at the university of Toronto, Texas and Michigan, as well as by the National Optical Astronomy Observatory in Arizona.

To date, approximately 63 supermassive black holes have been found sitting in the cores of nearby galaxies. The largest for more than three decades was a 6.3 billion solar mass black hole in the center of the nearby galaxy M87.

One of the newly discovered black holes is 9.7 billion solar masses and located in the elliptical galaxy NGC 3842, the brightest galaxy in the Leo cluster of galaxies, 320 million light-years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, the brightest galaxy in the Coma cluster about 336 million light-years from Earth in the direction of the constellation Coma Berenices.

According to McConnell, these black holes have an event horizon—the “abandon all hope” edge from which not even light can escape—that is 200 times the orbit of Earth, or five times the orbit of Pluto. Beyond the event horizon, each black hole has a gravitational influence that would extend over a sphere 4,000 light-years across.

“For comparison, these black holes are 2,500 times as massive as the black hole at the center of the Milky Way Galaxy, whose event horizon is one fifth the orbit of Mercury,” McConnell said.

The Brightest Galaxy in a Cluster
These 10 billion solar mass black holes have remained hidden until now, presumably because they are living in quiet retirement, Ma said. During their active quasar days some 10 billion years ago, they cleared out the neighborhood by swallowing vast quantities of gas and dust. The surviving gas became stars that have since orbited peacefully. According to Ma, these monster black holes, and their
equally monster galaxies that likely contain a trillion stars, settled into obscurity at the center of galaxy clusters.

Ma, a theoretical astrophysicist, decided to look for these huge black holes in relatively nearby clusters of elliptical galaxies as a result of her computer simulations of galaxy mergers.

Astronomers believe that many, if not all, galaxies have a massive black hole at the center, with the larger galaxies harboring larger black holes. The largest black holes are found in elliptical galaxies, which are thought to result from the merger of two spiral galaxies. Ma found, however, that mergers of elliptical galaxies themselves could produce the largest elliptical galaxies as well as supermassive black holes approaching 10 billion solar masses. These black holes can grow even larger by consuming gas left over from a merger.

“Multiple mergers are one way to build up these behemoths,” Ma said.

To look for these monster black holes, Ma teamed up with observational astronomers, including James Graham, a professor of astronomy at UC Berkeley and the University of Toronto, and Karl Gebhardt, a professor of astronomy at the University of Texas at Austin. Gebhardt had obtained the mass of the previous record holder in galaxy M87.

Using telescopes at the Keck and Gemini observatories in Hawaii and at McDonald Observatory in Texas, McConnell and Ma obtained detailed spectra of the diffuse starlight at the centers of several massive elliptical galaxies, each the brightest galaxy in its cluster. Keck observatory’s innovative Laser Guide Star Adaptive Optics were used for the observations. So far, they’ve analyzed the orbital velocities of stars in two galaxies and calculated the central masses to be in the quasar range. Having such huge masses contained within a volume only a few hundred light-years across led the astronomers to conclude that the masses were massive black holes.

“If all that mass were in stars, then we would see their light”, Ma said.

Modeling these massive galaxies required use of state-of-the-art supercomputers at the Texas Advanced Computing Center.

“For an astronomer, finding these insatiable black holes is like finally encountering people nine feet tall, whose great height had only been inferred from fossilized bones. How did they grow so large?” Ma said. “This rare find will help us understand whether these black holes had very tall parents or ate a lot of spinach.”

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Adapted from a UC Berkeley press release by Robert Sanders.

Keck Telescopes Find 18 New Exoplanets

December 2, 2011

KAMUELA, Hawaii—A whopping 18 new, bona fide exoplanets have been discovered and confirmed by a team of Caltech astronomers using the Keck Telescopes and two other ground-based observatories.

“It’s the largest single announcement of planets in orbit around stars more massive than the sun, aside from the discoveries made by the Kepler mission,” says John Johnson, assistant professor of astronomy at Caltech and the first author on the team’s paper, which was published in the December issue of The Astrophysical Journal Supplement Series. The Kepler mission is a space telescope that has so far identified more than 1,200 possible planets, though the majority of those have not yet been confirmed.

Using the Keck Observatory—with follow-up observations using the McDonald and Fairborn Observatories in Texas and Arizona, respectively—the researchers surveyed about 300 stars. They focused on those dubbed “retired” A-type stars that are more than one and a half times more massive than the sun. These stars are just past the main stage of their life—hence, “retired”—and are now puffing up into what’s called a subgiant star.

To look for planets, the astronomers searched for stars of this type that wobble, which could be caused by the gravitational tug of an orbiting planet. The wobble is given away by the fact that the light of those stars have a periodic lengthening and contracting of wavelengths due to the stars’ motion away from and toward the observer—better known as a Doppler shift. Using this, the team found 18 planets with masses similar to Jupiter’s.

This new bounty marks a 50 percent increase in the number of known planets orbiting massive stars and, according to Johnson, provides an invaluable population of planetary systems for understanding how planets—and our own solar system—might form. The researchers say that the findings also lend further support to the theory that planets grow from seed particles that accumulate gas and dust in a disk surrounding a newborn star.

According to this theory, tiny particles start to clump together, eventually snowballing into a planet. If this is the true sequence of events, the characteristics of the resulting planetary system—such as the number and size of the planets, or their orbital shapes—will depend on the mass of the star. For instance, a more massive star would mean a bigger disk, which in turn would mean more material to produce a greater number of giant planets.

In another theory, planets form when large amounts of gas and dust in the disk spontaneously collapse into big, dense clumps that then become planets. But in this picture, it turns out that the mass of the star doesn’t affect the kinds of planets that are produced.

So far, as the number of discovered planets has grown, astronomers are finding that stellar mass does seem to be important in determining the prevalence of giant planets. The newly discovered planets further support this pattern—and are therefore consistent with the first theory, the one stating that planets are born from seed particles.

“It’s nice to see all these converging lines of evidence pointing toward one class of formation mechanisms,” Johnson says.

The new batch of planets have yet another interesting pattern: their orbits are mainly circular, while planets around sunlike stars span a wide range of circular to elliptical paths. Johnson says he’s now trying to find an explanation.

For Johnson, these discoveries have been a long time coming. This latest find, for instance, comes from an astronomical survey that he started while a graduate student; because these planets have wide orbits, they can take a couple of years to make a single revolution, meaning that it can also take quite a few years before their stars’ periodic wobbles become apparent to an observer.

“I liken it to a garden—you plant the seeds and put a lot of work into it,” he says. “Then, a decade in, your garden is big and flourishing. That’s where I am right now. My garden is full of these big, bright, juicy tomatoes—these Jupiter-sized planets.”

The other authors on the The Astrophysical Journal Supplement Series paper, “Retired A stars and their companions VII. Eighteen new Jovian planets,” include former Caltech undergraduate Christian Clanton, who graduated in 2010; Caltech postdoctoral scholar Justin Crepp; and nine others from the Institute for Astronomy at the University of Hawaii; the University of California, Berkeley; the Center of Excellence in Information Systems at Tennessee State University; the McDonald Observatory at the University of Texas, Austin; and the Pennsylvania State University. The research was supported by the National Science Foundation and NASA.

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Adapted from a Caltech press release by Marcus Woo

TEDxHONOLULU - Dr. Michael Liu - Telescopes as Time Machines

November 21, 2011

Watch these 18 science-packed minutes from this recent live webcast of Dr. Mike Liu, a frequent Keck Telescope user.

Keck, Magellan & Hubble Telescopes Find Galactic Recyclers

November 17, 2011

Kamuela, HI - The secret of longevity is recycling, at least for galaxies, say astronomers who have used a trio of the world’s best telescopes to study the uncharted space around vibrant star-birthing galaxies and their not-so-vibrant siblings.

Galaxies learned to “go green” early in the history of the universe, continuously recycling immense volumes of hydrogen gas and heavy elements to build successive generations of stars stretching over billions of years. This recycling keeps galaxies from emptying their “fuel tanks” and therefore stretches out their star-forming epoch to over 10 billion years.

However, galaxies that ignite a rapid firestorm of star birth can blow away their remaining fuel, essentially turning off further star birth activity. This conclusion is supported by a series of observations by the 10-meter Keck I telescope, the Magellan Telescope and the Hubble Space Telescope.

In space, Hubble’s COS (Cosmic Origins Spectrograph) collected information about the gases surrounding scores of galaxies with the ultraviolet light from more distant bright quasars that shine through the gases. On the ground, the Keck I’s telescope’s LRIS instrument (Low Resolution Imaging Spectrograph) and Magellan’s MagE instrument gauged the distances to the galaxies, the masses of the stars in the galaxies, and even the rate at which some galaxies are forming stars.

The unraveling of galaxy-gas relationship was announced in three papers published in the Nov. 18 issue of the journal Science.

“Having both datasets (ground and space based) allows us to make that very important connection between the extended halo gas and the galaxy’s own stars and gas,” said astronomer Jessica Werk of the University of California’s Lick Observatory at U.C. Santa Cruz. Werk is a contributing author on all three of the Science papers and the lead author on a supporting paper in Astrophysical Journal, which is slated to be published in January. “With that we can confirm that the gas absorption we are seeing with COS is at the same distance as the galaxy we observe with Keck.”

Unexpected relationships popped out when the researchers compared the gases around galaxies to the galaxies themselves.

“What we ended up finding surprised us,” said Werk. “The galaxies that are actively forming stars are surrounded by extended, massive halos of oxygen-enriched gas—these halos contain nearly as much, if not more gas than is in the galaxy itself.”

Somewhat unexpectedly, these types of vast reservoirs of gas appear to be mostly absent from galaxies that are not currently forming stars, she explained.

“The average person perhaps pictures a galaxy as an organized, beautiful spiral structure filled with stars and gas,” Werk said. “We are now seeing a huge component of galaxies that has never been seen before—a very massive, oxygen-rich halo component that extends to large distances outside the visible spiral part of a galaxy—and it is changing our view of galaxy evolution.”

Among the key findings of the work is that the color and shape of a galaxy is largely controlled by gas flowing through an extended halo around it. All modern simulations of galaxy formation find that they cannot explain the observed properties of galaxies without modeling the complex accretion and “feedback” processes by which galaxies acquire gas and then later expel it after processing by stars. The three studies investigated different aspects of the gas recycling phenomenon.

“Our results confirm a theoretical suspicion that galaxies expel and can recycle their gas, but they also present a fresh challenge to theoretical models to understand these gas flows and integrate them with the overall picture of galaxy formation,” said Jason Tumlinson of the Space Telescope Science Institute in Baltimore, Maryland; a coauthor of one of the Science papers.

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[This press release is adapted from another by STScI]

Found: Pristine Gas From The Big Bang

November 10, 2011

Kamuela, HI – Two clumps of primordial gas from the dawn of time have been detected in deep space by astronomers using the 10-meter telescopes at the W. M. Keck Observatory.

The gas clouds are too diffuse to form stars and show virtually no signs of containing any “metals,” which is astronomer-speak for all elements heavier than hydrogen and helium – the two simplest and lightest elements in the universe. In fact the only elements astronomers have detected in the clouds are hydrogen and its heavier isotope, deuterium.

The lack of metals strongly suggests that the gases are reservoirs of the pristine material left over from the Big Bang. Because stars fuse atoms to make heavier elements, these gases have never been involved in any star making in the 2 billion years between the Big Bang and their discovery. In other words, they are the remnant gases that are unchanged since they were created in the first few minutes after the Big Bang.

“Despite decades of effort to find anything metal-free in the universe, Nature has previously set a limit to enrichment at no less than one-thousandth that found in the Sun,” said astronomer J. Xavier Prochaska of the University of California Observatories-Lick Observatory, U.C. Santa Cruz. “These clouds are at least 10 times lower than that limit and are the most pristine gas discovered in our universe.”

Prochaska has coauthored a paper reporting on the discovery with Michele Fumagalli of the U.C. Santa Cruz and John O’Meara of Saint Michael’s College in Vermont. The paper is scheduled to be published by the journal Science, on the Science Express website (http://www.sciencexpress.org) on Nov. 10.

“We’ve searched carefully for oxygen, carbon, nitrogen and silicon – the things that are found on Earth and the Sun in abundance,” Fumagalli said. “We don’t find a trace of anything other than hydrogen and deuterium.”

Exactly how they can detect dark, cold, diffuse gas about 12 billion light-years away is a story in itself.

“In this case we actually have to do a bit of a trick,” Prochaska explained. “We study the gas in silhouette.” A more distant quasar provides the light for this. The quasar light shines though the gas and the elements in the gas absorb very specific wavelengths of light, which can only be found by splitting the light into very detailed spectra to reveal the dark lines of missing light.

In other words, said Fumagalli, “All of the analysis is on the light we didn’t get.” The clouds absorb only a small fraction of the quasar light that makes it to Earth. “But the signatures of hydrogen absorption are obvious, so there’s no doubt there’s a lot of gas there.”

The blobs of pristine gas are good news to astronomers because they are confirmation of the theory of what the first elements were and how they were created in the Big Bang. Hydrogen, helium, lithium and boron are the lightest elements on the periodic table of elements and they were all created for the first time in what’s called the Big Bang nucleosynthesis (BBN).

“That theory has been very well tested at Keck as regards to hydrogen and its isotope deuterium,” said O’Meara. “One of the conundrums of that previous work, however, is that the gas also showed at least trace amounts of oxygen and carbon. The clouds that we have discovered are the first to match the full predictions of BBN.”

The discovery also reveals how different the early universe was from today – where it’s very hard to find any place without some “metals” caused by generations of element-building fusion reactors, a.k.a. stars.

“What excites me about this discovery is that there is an almost a range of 1,000,000 in the metallicity in gases at that time in the universe,” said Fumagalli. In other words, there were places like our Solar system – where metals are very abundant – and there were also places very unlike today, where metals were still virtually non-existent and the gases were unchanged since almost the beginning of time.

Keck Telescope Snaps Images of Asteroid’s Exit

November 9, 2011

Kamuela HI – One of the world’s largest optical/infrared telescopes has captured near-infrared light images of asteroid YU55 as it was departing its close flyby of Earth the night of Nov. 8, 2011. The observing run on the Keck II telescope was webcast live to a large audience on UStream directly from the Keck II Telescope Remote Operations room in Kamuela, Hawaii.

At the helm of the 10-meter telescope and using Keck’s pioneering adaptive optics to view YU55 were asteroid investigators William Merline and Peter Tamblyn of Southwest Research Institute, Boulder, Colo.; and Chris Neyman of Keck Observatory.

The first unprocessed infrared images of the coal-black asteroid appear to confirm that the asteroid does not have any small companion satellites and that it may be somewhat smaller than some researchers have suspected.

Asteroid YU55, made its closest approach to Earth - just 324,600 kilometers – on Nov. 8 at 3:26 pm U.S. PST. Merline’s research is funded by NASA’s Planetary Astronomy Program and NSF’s Planetary Astronomy Program. More updates and images are forthcoming.

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Youngest Planet Seen As It’s Forming

October 19, 2011

Kamuela, HI – The first direct image of a planet in the process of forming around its star has been captured by astronomers who combined the power of the 10-meter Keck telescopes with a bit of optical sleight of hand.

What astronomers are calling LkCa 15 b, looks like a hot “protoplanet” surrounded by a swath of cooler dust and gas, which is falling into the still-forming planet. Images have revealed that the forming planet sits inside a wide gap between the young parent star and an outer disk of dust.

“LkCa 15 b is the youngest planet ever found, about 5 times younger than the previous record holder,” said astronomer Adam Kraus of the University of Hawaii’s Institute for Astronomy. “This young gas giant is being built out of the dust and gas. In the past, you couldn’t measure this kind of phenomenon because it’s happening so close to the star. But, for the first time, we’ve been able to directly measure the planet itself as well as the dusty matter around it.”

Artist’s conception of the view near the planet LkCa 15 b. Credit: Karen L. Teramura, UH IfA

Kraus will be presenting the discovery at an Oct. 19 meeting at NASA’s Goddard Space Flight Center. The meeting follows the acceptance of a research paper on the discovery by Kraus and Michael Ireland (of Macquarie University and the Australian Astronomical Observatory), in The Astrophysical Journal (available at http://arxiv.org/abs/1110.3808)

The optical sleight of hand used by the astronomers is to combine the power of Keck’s Adaptive Optics with a technique called aperture mask interferometry. The former is the use of a deformable mirror to rapidly correct for atmospheric distortions to starlight. The latter involves placing a small mask with several holes in the path of the light collected and concentrated by a giant telescope. With that, the scientists can manipulate the light waves.

“It’s like we have an array of small mirrors,” said Kraus. “We can manipulate the light and cancel out distortions.” The technique allows the astronomers to cancel out the bright light of stars. They can then resolve disks of dust around stars and see gaps in the dusty layers where protoplanets may be hiding.

Figure 1 Left: The transitional disk around the star LkCa 15. All of the light at this wavelength is emitted by cold dust in the disk. the hole in the center indicates an inner gap with radius of about 55 times the distance from the Earth to the Sun. Right: An expanded view of the central part of the cleared region, showing a composite of two reconstructed images (blue: 2.1 microns, from November 2010; red: 3.7 microns) for LkCa 15. The location of the central star is also marked. Credit: Kraus & Ireland 2011

“Interferometry has actually been around since the 1800’s, but through the use of adaptive optics has only been able to reach nearby young suns for about the last 7 years.” said Dr. Ireland. “Since then we’ve been trying to push the technique to its limits using the biggest telescopes in the world, especially Keck.”

The discovery of LkCa 15 b began as a survey of 150 young dusty stars in star forming regions. That led to the more concentrated study of a dozen stars.

“LkCa 15 was only our second target, and we immediately knew we were seeing something new,” said Kraus. “We could see a faint point source near the star, so thinking it might be a Jupiter-like planet we went back a year later to get more data.”

Figure 2 The location of LkCa 15 can be found using this chart. Credit: Adam Kraus/IAU/Sky & Telescope

In further investigations at varying wavelengths, the astronomers were intrigued to discover that the phenomenon was more complex than a single companion object.

“We realized we had uncovered a super Jupiter-sized gas planet, but that we could also measure the dust and gas surrounding it. We’d found a planet, perhaps even a future solar system at its very beginning” said Kraus.

Drs. Kraus and Ireland plan to continue their observations of LkCa 15 and other nearby young stars in their efforts to construct a clearer picture of how planets and solar systems form.

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Oxygen: Breathing the Universe

October 18, 2011

Here is the video recording of the Oct. 13, 2011, Keck Observatory Astronomy Talk by Dr. Lisa Kewley, of the University of Hawaii’s Institute for Astronomy. The venue is the historic Kahilu Theatre in Waimea on the Big Island of Hawaii.

Part One

Part Two

Nobel Prize in Physics awarded for Accelerating Expansion of the Universe

October 5, 2011

The expansion of the universe is accelerating, and this is likely driven by dark energy, a mysterious repulsive force. Three astronomers won the Nobel prize on Tuesday for their research on exploding stars, or supernovae, that led to this profound cosmological conclusion. They are Saul Perlmutter of the Lawrence Berkeley National Laboratory in Berkeley, California, Brian P. Schmidt of the Australian National University in Weston Creek, Australia, and Adam G. Riess of the Space Telescope Science Institute and Johns Hopkins University in Baltimore, Maryland. Their discovery relied fundamentally on spectroscopy using the W. M. Keck Observatory and its LRIS spectrograph, in the period 1995 to 1997.

Perlmutter, Schmidt and Riess were members of two competing teams who were both studying the most distant supernovae. These Type Ia supernovae have been demonstrated to be “standard candles” and can thus yield relatively precise cosmological distances. The Keck spectra of the extremely distant supernova candidates were essential in order to indicate they are Type Ia, and to determine the redshift, or its velocity as seen from Earth, of the galaxy hosting the supernova. It was the redshifts and distances of a modest number of distant supernovae that revealed that the expansion of the universe was not slowing down, as was predicted, but in fact was inexplicably speeding up. The accelerating expansion of the Universe, first reported in 1998, was confirmed by the two separate groups. This accelerating cosmological expansion and the hypothesis that it is driven by dark energy has now become one of the most important areas of study in astronomy and physics today.

At the time, “We were a little scared,” Schmidt said. Subsequent cosmological measurements have confirmed that roughly 70 percent of the universe by mass or energy consists of this anti-gravitational force called dark energy.

In fact, Albert Einstein introduced this bizarre behavior with a fudge factor in his equations in 1917 to stabilize the universe against collapse. He later abandoned this idea, and then considered it his greatest blunder. “Every test we have made has come out perfectly in line with Einstein’s original cosmological constant in 1917,” Schmidt said.

In the years since then the three astronomers, along with their collaborators, have shared a number of awards, including the Shaw Prize in Astronomy, for this ground breaking research.

Perlmutter, who led the Supernova Cosmology Project out of Berkeley, will get half of the prize of 10 million Swedish kronor ($1.4 million). The other half will be shared between Dr. Schmidt, leader of the rival High-Z Supernova Search Team, and Riess, who was the lead author of the 1998 paper in The Astronomical Journal, in which the dark energy result was first published. They will receive their prizes in Stockholm on December 10.

“The recognition by the Nobel Committee of the importance of this work validates the enormous value to our society of ground-based optical / infrared astronomy,” said Taft Armandroff, Director of the W. M. Keck Observatory. “By making our two Keck telescopes and their instruments work at the highest performance, transformational science like that of Saul Perlmutter, Brian Schmidt and Adam Riess happens.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Universe’s “Standard Candles” Are White Dwarf Mergers

October 3, 2011

Berkeley — A new survey of distant Type Ia supernovae suggests that many if not most of these supernovae - key to astronomers’ conclusion that dark energy is accelerating the expansion of the universe - result when two white dwarf stars merge and annihilate in a thermonuclear explosion.

Evidence that Type Ia supernovae are caused by the merger of two white dwarfs - the so called double-degenerate theory - has been accumulating over the past two years, based on surveys by the Hubble Space Telescope and others. Before, astronomers favored the single-degenerate model: the idea that Type Ia’s result from the explosion of a white dwarf grown too fat by feeding on its normal stellar companion.

White dwarfs are dense, compact stars formed from normal stars like the sun once they exhaust their nuclear fuel and compress under their own weight.

The new survey using the Subaru Telescope in Hawaii and backed up by Keck Observatory observations, was conducted by a team of American, Israeli and Japanese astronomers and is the largest to date, having accumulated a sample of 150 distant supernovas that exploded between 5 and 10 billion years ago.

“The main goal of this survey was to measure the statistics of a large population of supernovae at a very early time, to get a look at the possible star systems,” said Dovi Poznanski, one of the main authors of the paper and a post-doctoral fellow at the University of California, Berkeley, and Lawrence Berkeley National Laboratory. “We need two white dwarfs merging to explain what we are seeing.”

The finding, when combined with previous surveys of closer Type Ia supernovae, suggests that astronomers surveying Type Ia supernovae may be seeing a mixture of single and double-degenerates. This does not, however, place in jeopardy the conclusion that the expansion of the universe is accelerating, said coauthor Alex Filippenko, UC Berkeley professor of astronomy.

“The tide is definitely turning, and these are the best data yet to support the double-degenerate theory,” he said. “But as long as Type Ia’s explode in the same way no matter what their origin, their intrinsic brightnesses should be the same and the distance calibrations would remain unchanged.”

Poznanski, Tel-Aviv University graduate student Or Graur, Filippenko and their colleagues will report their findings in the October 2011 issue of Monthly Notices of the Royal Astronomical Society (MNRAS).

“Over the past 14 years we used Type Ia supernovae to determine that the universe is actually accelerating in its expansion, under the influence of mysterious dark energy, but the nature of these events themselves is poorly understood and there is a fierce debate about how these explosions ignite,” said Poznanski.

“There are no good answers yet, and it could be that we are seeing a mix of the two types of explosions,” he said.

Though the two-faced nature of Type Ia supernovae still allows them to be used as calibratable candles to measure cosmic distance, Filippenko said, it might affect attempts to “quantify in detail the history of the expansion rate of the universe. The subtle differences between single- and double-degenerate models could introduce a systematic error that we’ll need to account for.”

The team also found that Type Ia supernovae were five times more common 5-10 billion years ago than today, probably because there were more young stars back then rapidly evolving into white dwarfs. Moreover, this study allowed the team to more accurately determine the production of iron over cosmic time, as Type Ia supernovae create iron through nuclear reactions when they explode.

To find their distant sample, the international team of astronomers exploited the enormous light collecting power of the Subaru Telescope’s Suprime-Camera on four separate occasions. They pointed the ground-based telescope, located atop Hawaii’s Mauna Kea volcano, toward a single field in the sky that was approximately the size of the full moon. Each run yielded about 40 supernovae among 150,000 galaxies.

Then they used the Keck telescopes on Mauna Kea to observe the galaxies where these explosions occurred. These observations were crucial for pinpointing the distance of these
events.

Future observations with the Hyper Suprime-Camera, which will be mounted on the Subaru Telescope, will be able to discover even larger and more distant supernova samples to test this conclusion.

Other authors on the paper include Dan Maoz, Naoki Yasuda, Tomonori Totani, Masataka Fukugita, Ryan J. Foley, Jeffrey M. Silverman, Avishay Gal-Yam, Assaf Horesh, and Buell
T. Jannuzi. The research was supported in part by the National Science Foundation.

Read the paper at: http://arxiv.org/abs/1102.0005

# # #

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

(Adapted from a press release issued by U.C. Berkeley)

How I Killed Pluto & Why It Had It Coming: The Video

September 29, 2011

This is a video recording of the Sept. 15, 2011, lecture by Caltech astronomer Mike Brown. This public lecture was held at Kahilu Theatre in Waimea, on the Big Island of Hawaii. In this talk he explains not only how Pluto was demoted to a dwarf planet, but his controversial role in “killing” Pluto. He is introduced by Taft Armandroff, director of the W. M. Keck Observatory.

PART 1

PART 2

Citizen Scientists, Kepler and Keck Uncover New Planets

September 21, 2011

Astronomers at Yale University have announced the discovery of the first two potential exoplanets found by the online citizen scientist Planet Hunters program. Users of the Planet Hunters program analyze scientific data collected by NASA’s Kepler mission to assist astronomers in finding planets orbiting nearby stars. The most likely exoplanet candidates are then studied using the 10-meter telescopes of the W.M. Keck Observatory in Hawaii to confirm the planets’ existence.

Since the online citizen science project Planet Hunters launched last December, 40,000 web users from around the world have been helping professional astronomers analyze the light from 150,000 stars in the hopes of discovering Earth-like planets orbiting around them. A new study on the discovery is slated to be published in the Monthly Notices of the Royal Astronomical Society.

“This is the first time that the public has used data from a NASA space mission to detect possible planets orbiting other stars,” said Yale astronomer and exoplanet expert Debra Fischer, who helped launch the citizen science project.

The candidate planets orbit their host stars with periods ranging from 10 to 50 days—much shorter than the 365 days it takes the Earth to orbit the Sun—and have radii that range in size from two-and-a-half to eight times Earth’s radius. Despite those differences, one of the two candidates could be a rocky, Earth-mass planet (as opposed to a giant gas planet like Jupiter), although they aren’t in the so-called “habitable zone” where liquid water, and therefore life as we know it, could exist.

Next, the professional astronomy team – a collaboration between astronomers at Yale, the University of Oxford and the Adler Planetarium in Chicago
—used the Keck Observatory in Hawaii to analyze the spectra of the host stars. The spectra reveal whether the stars are wobbling, and by how much and at what speed – all of which reveal clues to the planets orbiting them.

The Kepler team had already announced they had identified 1,200 exoplanet candidates and that they would follow up on the highest potential ones, but they had discarded the two found by Planet Hunters users for various technical reasons that led them to believe they weren’t promising candidates.

“These two candidates might have gone undetected without Planet Hunters and its citizen scientists,” said Meg Schwamb, a Yale researcher and Planet Hunters co-founder. “Obviously Planet Hunters doesn’t replace the analysis being done by the Kepler team. But it has proven itself to be a valuable tool in the search for other worlds.”

Users found the two candidates in the first month of Planet Hunters operations using data the Kepler mission made publicly available. The Planet Hunters group sent the top 10 candidates found by the citizen scientists to the Kepler team, who analyzed the data and determined that two of the 10 met their criteria for being classified as planet candidates. The two candidates were flagged as potential planets by several dozen different Planet Hunters users, as the same data are analyzed by more than one user.

“Scientists on the Kepler team obtained the data, but the public helped finance the project with their tax dollars,” Fischer said. “It’s only right that this data has been pushed back into the public domain, not just as scientifically digested results but in a form where the public can actively participate in the hunt. The space program is a national treasure—a monument to America’s curiosity about the Universe. It is such an exciting time to be alive and to see these incredible discoveries being made.”

Planet Hunters users are now sifting through the next 90 days of Kepler data in the hopes of adding to the count. “This is what we found after just a preliminary glance through the first round of Kepler data,” Fischer said. “There’s no doubt that, with each new round of data, there will be more discoveries to come.”

# # #

Learn more about Planet Hunters:
http://www.planethunters.org
Watch a video of Planet Hunters co-founders Debra Fischer and Kevin Schawinski explaining the project:
http://www.youtube.com/user/YaleUniversity#p/search/0/18NCx-iBHBQ
The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which removes much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

(Adapted from a press release by Yale University)

Uncovering the Secrets of the Great Supernova

August 26, 2011

Kamuela, HI – A once-in-a-lifetime nearby stellar explosion now unfolding in a neighboring galaxy has astronomers at the W. M. Keck Observatory scrambling to ask questions that can’t be answered at any other ground-based telescope in the world. The first big question: What causes this pivotally important type of stellar cataclysm?

Observing this spectacular supernova, dubbed PTF11kly, began on August 24, with the detection of the explosion in the nearby Pinwheel Galaxy, a.k.a. M101, by the automated Palomar Transient Factory (PTF) survey. That survey is designed to detect short-lived astronomical events as they happen.

Next, the brightening point of light was observed by the Grand Canary Telescope in the Atlantic and the star’s light was split into the first information-rich spectrum. Then, as the Earth turned and presented different telescopes to that part of the sky, the Lick Telescope in California got another spectrum of the exploding star, followed soon by a very high quality spectrum from the HIRES instrument on the Keck I telescope in Hawai’i.

Both Lick and Keck astronomers confirmed that the explosion is a Type Ia supernova – the kind that pop off occasionally in very distant galaxies. There has not been another Type Ia supernova this close to Earth in decades, and none have ever before been caught so early in the process of this type of stellar death.

“Nearby Type Ia’s are very rare,” said postdoctoral astronomy researcher Brad Cenko of the University of California at Berkeley.

Astronomers have long adored Type Ia supernovae because they seem to behave in a very predictable manner: brightening and reaching the same luminosity, before fading away. As a result when they happen in very distant galaxies, they are recognizable and can be used as “standard candles” to measure cosmic distances.

Such measurements led to one of the biggest cosmological discoveries of recent years: galaxies are moving further apart and the universe is expanding at an accelerating rate. That discovery, in turn, pointed to the existence of a sort of weird anti-gravity force astronomers call “dark energy.”

“Given the importance of this supernova for both the Type Ia supernova distance scale and for constraining the progenitors of Type Ia’s, Keck Observatory responded rapidly and deployed assets to acquire both spectroscopy and adaptive optics imaging,” said Keck Observatory Director Taft Armandroff. Keck adaptive optics cancel out Earth’s atmospheric distortions to starlight.

Astronomers do not really know what causes Type Ia supernova, despite their importance. And that is why having one occur in a nearby galaxy and be studied so soon after its explosion began is so exciting for astronomers.

“Type Ia supernovae underlie one of the most important astronomical discoveries in the last few decades,” Cenko said. “But we still don’t know what their progenitor systems are.”

It’s generally believed that there are at least two stars involved in creating a Type Ia supernova. One star is most likely a white dwarf – a kind of dead star. What the other one is, no one is exactly sure. It could be another white dwarf, main sequence star (like our sun) or a red giant star.

One way to find out is look at high-resolution images of the Pinwheel Galaxy taken by the Hubble Space Telescope before August 25 and see if there was a star in the same location.

“Keck and Hubble are pretty well matched in terms of spatial resolution,” said Keck support astronomer Jim Lyke. “So we can do a direct comparison.”

“We need very accurate images at very high resolution to match Hubble images,” agreed Lawrence Berkeley Laboratory astronomer Peter Nugent, who is the lead of the PTF Type Ia supernova program and chiefly responsible for the discovery of PTF11kly. The only way to do that is with Keck adaptive optics.

So in addition to gathering spectra of the supernova, astronomers started on the night of August 25 to take pictures of the supernova with the Keck II telescope adaptive optics system. Their hope is to get a very precise location of the star in the Pinwheel Galaxy so that they can look at those Hubble images and see if there was anything – like a red giant – there beforehand.

“If it was two white dwarfs it would be too faint to see,” said Cenko. Even if nothing is found in Hubble images, it will still be useful, he said, because it will put some limits on how large the stars could be to create a Type Ia supernova, and bolster the theory that two white dwarfs are the cause.

Another source of clues to the cause of the supernova are changes in the spectra as the explosion continues, Cenko explained. If, for instance, the companion star to the white dwarf was large, it would have likely shed lots of material in its final death throes. Then, when the explosion followed, that same material would be hit by the explosion itself. The shock waves of those collisions would create telltale signals in the spectra of the star as its explosion continues to expand into space.

“Because we don’t know the progenitor system (of Type Ia supernovae) we don’t have a good grasp on how diverse the Type Ia class might be,” said Joshua Bloom, another UC Berkeley astronomer who is leading the Keck research team. “It is a bit troubling that we really don’t know.”

But with the advent of the Pinwheel supernova, hopes are high that a lot more will be learned about these cosmic yardsticks.

# # #

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Ice & Maybe Methane on ‘Snow White’ Dwarf Planet

August 22, 2011

Ancient slush-spewing volcanoes slopped water ice across half the surface of the so-called “Snow White” world, say astronomers studying the distant dwarf planet 2007 OR10. Although it will take the giant W. M. Keck Observatory telescopes to be sure, the latest findings from the Magellan Baade Telescope in Chile also suggest that the red-tinged dwarf planet also may be covered in a thin layer of methane, the remnants of an atmosphere that’s slowly being lost into space.

“You get to see this nice picture of what once was an active little world with water volcanoes and an atmosphere, and it’s now just frozen, dead, with an atmosphere that’s slowly slipping away,” says Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy at California Institute of Technology (Caltech), who is the lead author on a paper to be published in the Astrophysical Journal Letters describing the findings. The paper is now in press.

Snow White—which was discovered in 2007 as part of the PhD thesis of Brown’s former graduate student Meg Schwamb—orbits the sun at the edge of the solar system and is about half the size of Pluto, making it the fifth largest dwarf planet. At the time, Brown had guessed incorrectly that it was an icy body that had broken off from another dwarf planet named Haumea; he nicknamed it Snow White for its presumed white color.

Soon, however, follow-up observations revealed that Snow White is actually one of the reddest objects in the solar system. A few other dwarf planets at the edge of the solar system are also red. These distant dwarf planets are themselves part of a larger group of icy bodies called Kuiper Belt Objects (KBOs). As far as the researchers could tell, Snow White, though relatively large, was unremarkable—just one out of more than 400 potential dwarf planets that are among hundreds of thousands of KBOs.

“With all of the dwarf planets that are this big, there’s something interesting about them—they always tell us something,” Brown says. “This one frustrated us for years because we didn’t know what it was telling us.” At that time, the Near Infrared Camera (NIRC) at the Keck Observatory— which Caltech professor of physics Tom Soifer and chief instrument scientist Keith Matthews helped design in the 1990s—was the best instrument astronomers had to study KBOs, according to Brown. But NIRC had just been retired, so no one could observe 2007 OR10 in detail. “It kind of languished,” he says.

Meanwhile, Adam Burgasser, a former graduate student of Brown’s and now a professor at UC San Diego, was helping to design a new instrument called the Folded-port Infrared Echellette (FIRE). Last fall, Brown, Burgasser, and postdoctoral scholar Wesley Fraser used this instrument with the 6.5-meter Magellan Baade Telescope in Chile to take a closer look at 2007 OR10.

As expected, Snow White was red. But to their surprise, the spectrum revealed that the surface was covered in water ice. “That was a big shock,” Brown says. “Water ice is not red.” Although ice is common in the outer solar system, it’s almost always white.

There is, however, one other dwarf planet that’s both red and covered with water ice: Quaoar, which Brown helped discover in 2002. Slightly smaller than Snow White, Quaoar is still big enough to have had an atmosphere and a surface covered with volcanoes that spewed an icy slush, which then froze solid as it flowed over the surface.

But because Quaoar isn’t as big as dwarf planets like Pluto or Eris, it could not hold onto volatile compounds like methane, carbon monoxide, or nitrogen as long. A couple of billion years after Quaoar formed, it began to lose its atmosphere to space; now, all that remains is some methane. Over time, exposure to the radiation from space turned that methane—which consists of a carbon atom bonded to four hydrogen atoms—into long hydrocarbon chains, which look red. Like the frost that covers a lawn on a cold morning, the irradiated methane sits on Quaoar’s icy surface, giving it a rosy hue.

The spectrum of 2007 OR10 looks similar to Quaoar’s, suggesting that what happened on Quaoar also happened on 2007 OR10. “That combination—red and water—says to me, ‘methane,’” Brown explains. “We’re basically looking at the last gasp of Snow White. For four and a half billion years, Snow White has been sitting out there, slowly losing its atmosphere, and now there’s just a little bit left.”

Although Snow White’s spectrum clearly shows the presence of water ice, Brown says, the evidence for methane is not yet definitive. To find out, the astronomers will have to use a big telescope like the one at the Keck Observatory. If it turns out that Snow White does indeed have methane, it will join Quaoar as one of only two dwarf planets that straddle the border between the handful of objects large enough to hold onto volatile compounds, and the smaller bodies that make up the vast majority of KBOs.

Keck Observatory Director Taft Armandroff commented “The work of Mike Brown and his team is revealing some of the least understood objects in our solar system. We eagerly await the team’s use of Keck Observatory’s infrared spectrographs to gain greater understanding of Snow White and her outer solar system counterparts.”

Another task, Brown says, is to give the dwarf planet an official name, since “Snow White” was just a nickname he and his colleagues used. Besides, the moniker no longer makes sense for describing this very red object. Before the discovery of water ice and the possibility of methane, “2007 OR10” might have sufficed for the astronomy community, since it didn’t seem noteworthy enough to warrant an official name. “We didn’t know Snow White was interesting,” Brown says. “Now we know it’s worth studying.”

To learn more, visit www.mikebrownsplanets.com. The research described in the Astrophysical Journal Letters paper, “The surface composition of large Kuiper Belt Object 2007 OR10,” was supported by the NASA Planetary Astronomy program.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

(Adapted from a press release written by Marcus Woo, Caltech)

Found: Heart of Darkness

July 28, 2011

Kamuela, HI – Astronomers using the 10-meter Keck II telescope in Hawaii have confirmed in a new paper that a troupe of about 1,000 small, dim stars just outside the Milky Way comprise the darkest known galaxy, as well as something else: a treasure trove of ancient stars.

By “dark” astronomers are not referring to how much light the galaxy, called Segue 1, puts out, but the fact that the dwarf galaxy appears to have 3,400 times more mass than can be accounted for by its visible stars. In other words, Segue 1 is mostly an enormous cloud of dark matter decorated with a sprinkling of stars.

The initial announcement of the “Darkest Galaxy” was made two years ago by Marla Geha, a Yale University astronomer, Joshua Simon from the Carnegie Institution of Washington, and their colleagues. This original claim was based on data from the Sloan Digital Sky Survey and the Keck II telescope. Those observations indicated the stars were all moving together and were a diverse group, rather than simply a cluster of similar stars that had been ripped out of the nearby and more star-rich Sagittarius dwarf galaxy. A competing group of astronomers at Cambridge University were, however, not convinced.

So Simon, Geha and their group returned to Keck and went to work with the telescope’s Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS) to measure how the stars move not just in relation to the Milky Way, but also in relation to each other.

If the 1,000 or so stars were all there was to Segue 1, with just a smidgeon of dark matter, the stars would all move at about the same speed, said Simon. But the Keck data show they do not. Instead of moving at a steady 209 km/sec relative to the Milky Way, some of the Segue 1 stars are moving at rates as slow as 194 kilometers per second while others are going as fast as 224 kilometers per second.

“That tells you Segue 1 must have much more mass to accelerate the stars to those velocities,” Geha explained. The paper confirming Segue 1’s dark nature appeared in the May 2011 issue of The Astrophysical Journal.

The mass required to cause the different star velocities seen in Segue 1 has been calculated at 600,000 solar masses. But there are only about 1,000 stars in Segue 1, and they are all close to the mass of our Sun, Simon said. Virtually all of the remainder of the mass must be dark matter.

Stellar Old Folks Home
Equally exciting news from Segue 1 is its unusual collection of nearly primordial stars. One way to tell how long ago a star formed is by its heavy element content, which can be gleaned from the characteristic absorption features in the star’s spectrum. Very old or primitive stars come from a time when the universe was young and few large stars had yet grown old enough to fuse lightweight atoms like hydrogen and helium into heavier elements like iron and oxygen. Early, and therefore ancient, stars that formed from early gas clouds are therefore very low in heavy elements.

The researchers managed to gather iron data on six stars in Segue 1 with the Keck II telescope, and a seventh Segue 1 star was measured by an Australian team using the Very Large Telescope. Of those seven, three proved to have less than one 2,500th as much iron as our own Sun.

“That suggests these are some of the oldest and least evolved stars that are known,” said Simon.

Searches for such primitive stars among the Milky Way’s billions have yielded less than 30.

“In Segue 1 we already have 10 percent of the total in the Milky Way,” Geha said. “For studying these most primitive stars, dwarf galaxies are going to be very important.”

Dark Matter Demolition Derby
The confirmation of the large concentration of dark matter in Segue 1 underscores the importance of other research that has focused on Segue 1. In particular, some researchers have been looking with the space-based Fermi Gamma Ray Telescope in hopes of catching sight of a faint glimmer of gamma rays which could be created, theoretically, by the collision and annihilation of pairs of dark matter particles.

So far the Fermi telescope has not detected anything of the sort, which isn’t entirely surprising and doesn’t mean the dark matter isn’t there, said Simon.

“The current predictions are that the Fermi telescope is just barely strong enough or perhaps not quite strong enough to see these gamma rays from Segue 1,” Simon explained. So there are hopes that Fermi will detect at least the hint of a collision.
“A detection would be spectacular,” said Simon. “People have been trying to learn about dark matter for 35 years and not made much progress. Even a faint glow of the predicted gamma rays would be a powerful confirmation of theoretical predictions about the nature of dark matter.”

In the meantime, astronomers suspect there are other, perhaps even darker dwarf galaxies hovering around the Milky Way, waiting to be discovered. “We’d like to find more objects like Segue 1,” Simon said.

Black Hole Eats Star, Belches Gamma Rays

June 17, 2011

Berkeley — A bright flash of gamma rays discovered on March 28 by the Swift satellite and studied in other wavelengths by Keck, Gemini North and other telescopes, may have been the death rattle of a star falling into a massive black hole and being ripped apart, according to a team led by astronomers at the University of California, Berkeley.

When the Swift Gamma Burst Mission spacecraft first detected the flash within the constellation Draco, astronomers thought it was a gamma-ray burst from a collapsing star and designated it GRB 110328A. On March 31, however, UC Berkeley’s Joshua Bloom sent out an email circular suggesting that it wasn’t a typical gamma-ray burst at all, but a high-energy jet produced as a star about the size of our sun was shredded by a black hole a million times more massive.

Careful analysis of the Swift data and subsequent observations by the Hubble Space Telescope and the Chandra X-ray Observatory confirmed Bloom’s initial insight. The details are published online today (Thursday, June 16) in Science Express, a rapid publication arm of the journal Science.

“This is truly different from any explosive event we have seen before,” Bloom said.

What made this gamma-ray flare, called Sw 1644+57, stand out from a typical burst was its long duration and the fact that it appeared to come from the center of a galaxy nearly 4 billion light years away. Since most, if not all, galaxies are thought to contain a massive black hole at the center, a long-duration burst could conceivably come from the relatively slow tidal disruption of an infalling star, the astronomers said.

“This burst produced a tremendous amount of energy over a fairly long period of time, and the event is still going on more than two and a half months later,” said Bloom, an associate professor of astronomy at UC Berkeley. “That’s because as the black hole rips the star apart, the mass swirls around like water going down a drain, and this swirling process releases a lot of energy.”

Bloom and his colleagues propose in their Science Express paper that some 10 percent of the infalling star’s mass is turned into energy and irradiated as X-rays from the swirling accretion disk or as X-rays and higher energy gamma rays from a relativistic jet that punches out along the rotation axis. Earth just happened to be in the eye of the gamma-ray beam.

Bloom draws an analogy with a quasar, which is a distant galaxy that emits bright, high-energy light because of the massive black hole at its center gobbling up stars and sending out a jet of X-rays along its rotation axis. Observed from an angle, these bright emissions are called active galactic nuclei, but when observed down the axis of the jet, they’re referred to as blazars.

“We argue that this must be jetted material and we’re looking down the barrel,” he said. “Jetting is a common phenomenon when you have accretion disks, and black holes actually prefer to make jets.”

Looking back at previous observations of this region of the cosmos, Bloom and his team could find no evidence of X-ray or gamma-ray emissions, leading them to conclude that this is a “one-off event,” Bloom said.

“Here, you have a black hole sitting quiescently, not gobbling up matter, and all of a sudden something sets it off,” Bloom said. “This could happen in our own galaxy, where a black hole sits at the center living in quiescence, and occasionally burbles or hiccups as it swallows a little bit of gas. From a distance, it would appear dormant, until a star randomly wanders too close and is shredded.”

Probable tidal disruptions of a star by a massive black hole have previously been seen at X-ray, ultraviolet and optical wavelengths, but never before at gamma-ray energies. Such random events, especially looking down the barrel of a jet, are incredibly rare, “probably once in 100 million years in any given galaxy,” said Bloom. “I would be surprised if we saw another one of these anywhere in the sky in the next decade.”

The astronomers suspect that the gamma-ray emissions began March 24 or 25 in the uncatalogued galaxy at a redshift of 0.3534, putting it at a distance of about 3.8 billion light years. Bloom and his colleagues estimate that the emissions will fade over the next year.

“We think this event was detected around the time it was as bright as it will ever be, and if it’s really a star being ripped apart by a massive black hole, we predict that it will never happen again in this galaxy,” he said.

Bloom’s colleagues include UC Berkeley theoretical physicist Elliot Quataert, who models the production of jets from accretion disks, and UC Berkeley astronomers S. Bradley Cenko, Daniel A. Perley, Nathaniel R. Butler, Linda E. Strubbe, Antonino Cucchiara, Geoffrey C. Bower and Adam N. Morgan; Dimitrios Giannios and Brian D. Metzger of Princeton University; Andrew J. Levan of the University of Warwick, Coventry, United Kingdom; Nial R. Tanvir, Paul T. O’ Brien, Andrew R. King and Sergei Nayakshin of the University of Leicester in the U.K.; Fabio De Colle, Enrico Ramirez-Ruiz and James Guillochon of UC Santa Cruz; William H. Lee of the Universidad Nacional Autonoma de México in Mexico City; Andrew S. Fruchter of the Space Telescope Science Institute in Baltimore, Md.; and Alexander J. van der Horst of the Universities Space Research Association in Huntsville, Ala.

Levan is first author of the companion Science Express paper, and leader of the Chandra and Hubble Space Telescope observation team.

Bloom and his laboratory are supported by grants from NASA and the National Science Foundation.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

For more information:

• “A Possible Relativistic Jetted Outburst from a Massive Black Hole Fed by a Tidally Disrupted Star” (June 16, 2011, Science Express)
•April 7 NASA press release about unusual gamma-ray burst
•Swift mission home page

The original version of this press release is posted at the UC Berkeley News Center.

Lasers Spectacular

June 8, 2011

The new laser on the Keck I telescope has inspired two avid Mauna Kea photographers to capture the light show in a series of stunning images and videos. We’ve collected some of their work here for your entertainment and inspiration. The following video is by Andrew Cooper who assembled it with more than 90 separate one-minute images he took on the night of May 26, 2011.

Lasers 3 over Mauna Kea from Andrew Cooper on Vimeo.

This second video was shot in March by Dan Birchall, of the Subaru Telescope.Dan has a nice vantage point on the ground of Subaru, south and a bit below the Keck Observatory.

Finally, we have this beautiful panoramic image by Dan Birchall. His position was to the west of the Subaru Telescope, which can be seen to the far right in this image. Keck I is in the middle and Keck II to the left. The Milky Way stretches across the sky.

Nature’s Best Magnifying Glass Views Early Spiral Galaxy

May 25, 2011

Kamuela, HI – Astronomers in Hawaii have plucked unprecedented details from the life of an early galaxy using an unusually lucid gravitational lens coupled with the powerful 10-meter Keck II Telescope on Mauna Kea.

Gravitational lenses are Nature’s largest telescopes, created by colossally massive clusters of thousands of galaxies that bend and magnify the light of more distant objects behind them in a way similar to a glass lens. But gravitational lenses are far from perfect. Though they make very distant galaxies from the early universe visible to telescopes, they also put the images through a cosmic blender. As a result, the smeared and distorted images don’t offer much in the way of direct information about what the earliest galaxies looked like.

But that is not the case for an elegant little spiral galaxy called Sp1149, located 9.3 billion light-years away. The galaxy’s image has come through a gravitational lens magnified 22 times and fairly intact, as seen in a Hubble Space Telescope image. The image was first observed in detail by the University of Hawaii’s Tiantian Yuan and was initially taken by Harald Ebeling, also of Hawaii, and published by Graham P. Smith and colleagues in 2009. The giant cluster of galaxies that created the lens is located in the vast expanse of space between Sp1149 and Earth, and appears beside Sp1149 in the Hubble image.

The secret to Sp1149’s successful magnification is that it is in a special position behind the cluster which allows its light to be bent equally in all directions, explained astronomer Lisa Kewley of the University of Hawaii at Manoa.

“We’re lucky that it’s not being terribly distorted,” said Kewley. “Something so far away that’s not lensed would look like a blurred dot.”

The fact that you can distinguish the galactic core and spiral arms of Sp1149, plus the fact that we are seeing the galaxy as it was when the universe was only a third of its current age, makes it a great specimen for testing different models of how galaxies are born and then grow up to be places like our own Milky Way.

To that end, Yuan, Kewley and their colleagues aimed the Keck II Telescope at Sp1149. With the help of Laser Guide Star Adaptive Optics (which cancels out much of the optical distortions caused by Earth’s atmosphere) and the OSIRIS instrument (which filters out the noise created by hydroxyl molecules in Earth’s atmosphere) the researchers were able to get an unprecedented look at the distributions of elements in Sp1149. Oxygen, in particular, is very revealing because the element accumulates more in the older stellar neighborhoods – the parts of galaxies where stars have lived and died more. In the case of Sp1149, the oxygen distribution spoke volumes.

“The oxygen in the spiral galaxy was much more concentrated at the center,” said Kewley. “They had a lot of star formation at the center.”

This sharp oxygen gradient, from core to outer disk, suggests that stars in the cores of galaxies form first and create the oldest stellar neighborhoods in Sp1149, followed later by the disk and arms. That supports what’s called the inside-out model of galactic evolution, she said.

“This is an idea that has been out there,” explained Kewley. “Some models predict the opposite. “It’s been an open question for a long time.” What has been needed was something other than a local galaxy to study to see how the oxygen gradients looked much earlier in a galaxy’s history. Without that, astronomers would have nothing but middle aged galaxies to judge from. They would be like a biologist studying the lives of frogs without ever having seen a tadpole.

“This is the first time anyone has done such a detailed and precise oxygen gradient that wasn’t on a local galaxy,” said Kewley. Yuan, Kewley and their colleagues published their discovery in the journal May 1 issue of Astrophysical Journal Letters (available online at http://arxiv.org/abs/1103.3277)

Now that the team has found one galactic tadpole, they are hunting for more, said Kewley. They also are hoping to study some galaxies that are midway between the ages of our local galaxies and Sp1149. With these samples from different ages, Kewley and her colleagues hope to piece together a much clearer life history of galaxies like our own.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Children’s Astro Haiku Contest Winners

May 17, 2011

Kamuela, HI – The W. M. Keck Observatory’s mission is to advance the frontiers of astronomy and share our discoveries with the world. Today that mission extends to sharing the creativity of some of tomorrow’s explorers who recently sat down to write their thoughts about space and astronomy as haiku poems for the Keck Observatory Astro Haiku Contest.

All entries were composed by children on the spot at the Keck booth at the Astro Day event in Hilo on May 7. The poems span topics such matters as celestial navigation, black holes, space exploration and alien life.

“It’s impressive that these kids can stop in the middle of a busy shopping center and compose such thoughtful poetry about space,” said Keck astronomer Marc Kassis, a judge of the contest. “I was impressed by their creativity.”

Haiku is a three line poem, with the first line having a total of five syllables, the second line having seven and the third line having five. The only other requirement was an astronomical theme. Winners will receive a year subscription to an age appropriate science magazine.

Here are the winning entries and runners up:

4-6 Years Category: Micah Timbresa (6), Hilo

The Moon is so bright
The stars are twinkling tonight
Makes me smile so much

Micah will receive a year subscription to Click magazine

7-10 Years Category: Kameanani Miyasaki (8), Hilo

Stars shine bright at night
They show me direction too
I can follow it

Kameanani will receive a year subscription to Ask magazine

11-13 Years Category: Grace Morita (12), Hilo

Black holes aren’t so cool
They’ll pull you in and stretch you
‘cause their gravity

Grace will receive a year subscription to Odyssey magazine

14-18 Years Category: Leo Tanaka-Lee (14), Keaau

A connect-the-dots
Activity far away
In the midnight sky

Leo will receive a year subscription to Astronomy magazine

Runners up:

A star and a Earth
Planetarium is fun
The Moon has a bug
- Dustin Sumitani (4), Hilo

Days end begins with
The end of the Sun’s flight and
A bright starlit night
- Logan Sato, (12) Hilo

Orion’s belt shine
Constellation of hunter
Injures Scorpius
- Logan Kuniyuki, (9) Hilo

Glowing sphere of light
The Moon shining in the night
Always there for me
- Emerson Aynessazian (9), Pahoa

Looking in the night
I dream of alien life
Do you think it’s real?
- Brieann Yoshiwa (9), Hilo

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Keck & NASA Telescopes Reveal Surprisingly Young Galaxy

April 12, 2011

WASHINGTON—Astronomers have uncovered one of the youngest galaxies in the distant universe, with stars that formed 13.5 billion years ago, a mere 200 million years after the big bang. The finding addresses questions about when the first galaxies arose, and how the early universe evolved.

NASA’s Hubble Space Telescope was the first to spot the newfound galaxy. Detailed observations from the W.M. Keck Observatory on Mauna Kea in Hawaii revealed the observed light dates to when the universe was only 950 million years old; the universe formed about 13.7 billion years ago.

Infrared data from both Hubble and NASA’s Spitzer Space Telescope revealed the galaxy’s stars are quite mature, having formed when the universe was just a toddler at 200 million years old.

“This challenges theories of how soon galaxies formed in the first years of the universe,” said Johan Richard of the Centre de Recherche Astronomique de Lyon, Université Lyon 1 in France, lead author of a new study accepted for publication in the Monthly Notices of the Royal Astronomical Society. “It could even help solve the mystery of how the hydrogen fog that filled the early universe was cleared.”

This galaxy is not the most distant ever observed, but it is one of the youngest to be observed with such clarity. Normally, galaxies like this one are extremely faint and difficult to study, but, in this case, nature has provided the astronomers with a cosmic magnifying glass. The galaxy’s image is being magnified by the gravity of a massive cluster of galaxies parked in front of it, making it appear 11 times brighter. This phenomenon is called gravitational lensing.

“Without this big lens in space, we could not study galaxies this faint with currently available observing facilities,” said co-author Eiichi Egami of the University of Arizona in Tucson. “Thanks to nature, we have this great opportunity to see our universe as it was eons ago.”

The findings may help explain how the early universe became “reionized.” At some point in our universe’s early history, it transitioned from the so-called dark ages to a period of light, as the first stars and galaxies began to ignite. This starlight ionized neutral hydrogen atoms floating around in space, giving them a charge. Ultraviolet light could then travel unimpeded through what had been an obscuring fog.

The discovery of a galaxy possessing stars that formed only 200 million years after the big bang helps astronomers probe this cosmic reionization epoch. When this galaxy was developing, its hot, young stars would have ionized vast amounts of the neutral hydrogen gas in intergalactic space. A population of similar galaxies probably also contributed to this reionization, but they are too faint to see without the magnifying effects of gravitational lensing.

NASA’s James Webb Space Telescope (JWST), scheduled to launch later this decade, will be able to see these faint galaxies lacking magnification. A successor to Hubble and Spitzer, JWST will see infrared light from the missing population of early galaxies. As a result, the mission will reveal some of our universe’s best-kept secrets.

“Seeing a galaxy as it appeared near the beginning of the universe is an awe-inspiring feat enabled by innovative technology and the fortuitous effect of gravitational lensing,” said Jon Morse, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “Observations like this open a window across space and time, but more importantly, they inspire future work to one day peer at the stars that lit up the universe following the big bang.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

For more information about Spitzer and Hubble, visit:

http://www.nasa.gov/spitzer and http://www.nasa.gov/hubble

Keck Telescope Images Super-Luminous Supernova

March 31, 2011

Austin, Texas - The Keck I Telescope has played a key role in unraveling the mysteries of one of the brightest supernovas ever discovered.

The supernova, called Supernova 2008am, is 3.7 billion light-years away from Earth. At its peak luminosity, it was over 100 billion times brighter than the Sun. It emitted enough energy in one second to satisfy the power needs of the United States for one million times longer than the universe has existed. In-depth studies of this supernova, including images from the Keck I Low Resolution Imaging Spectrometer, are helping a team of astronomers to understand the science behind this new class of exploding stars.

Supernova 2008am was discovered by astronomers led by graduate student Emmanouil “Manos” Chatzopoulos and Dr. J. Craig Wheeler of The University of Texas at Austin. It is the latest addition to a new class of exploding stars that astronomers identified a few years ago. Supernova 2008am is one of the most intrinsically bright exploding stars ever observed. The team’s research reveals that this supernova is the brightest “self-interacting” supernova yet discovered. In this type of stellar explosion, the extreme brightness is caused by interaction between the explosion shockwave and a shell of material previously expelled from the star. This research is published in the current issue of The Astrophysical Journal.

The supernova was discovered by the ROTSE Supernova Verification Project (RSVP, formerly called the Texas Supernova Search), which uses the 18-inch robotic ROTSE IIIb Telescope at The University of Texas at Austin’s McDonald Observatory. It was followed up by astronomers using some of the world’s largest ground-based telescopes, as well as telescopes in space, in a variety of wavelengths. These include the Keck I Telescope, the Hobby-Eberly Telescope, PAIRITEL, the Very Large Array, and the Swift satellite.

Chatzopoulos’ detailed analysis of the light from SN 2008am revealed that it is not a pair-instability supernova, the explosion of a massive star the light from which is powered by radioactive decay.
Rather, this supernova’s extraordinary luminosity most likely comes from interaction between the debris from the star’s explosion running into an envelope of gas around the star that the star had previously ejected. This model is called “circumstellar interaction.”

The researchers suspect that the progenitor star for this supernova might have been of the type known as a “luminous blue variable.” These massive stars puff off layers of material in episodes. The most famous example is Eta Carinae.

Prior to this discovery, the Texas Supernova Search found the first two “brightest supernovae ever” in SN 2005ap and 2006gy. The group has found five of the dozen published examples of this new class of stars, which it has dubbed “super-luminous supernovae,” or SLSNe.

SLSNe are about 100 times brighter than standard core-collapse supernovae, but extremely rare. Normal supernovae go off at a rate of about one per century in a galaxy; SLSNe may be more than a thousand times more rare.

“We’re now in the process of converting our discoveries into real science rather than just a new thing,” Wheeler said. “That makes it a little bit less flashy, but of course that’s where the science really is, digging deeply into the nature of these very bright events. This new supernova has given us important new clues to their behavior.”

Studies of SLSNe have led to new insights, Chatzopoulos said. “For the first time, we’re probing high-mass stellar death. The traditional ideas we have about how supernovae are powered, why they are so bright, do not seem to apply for the case of these super-luminous supernovae. There are other mechanisms involved.”

Not all SLSNe are the same. “There’s a variety of progenitor stars that can give different outcomes,” Chatztopoulos said. “It’s a zoo.”
The common factor is their luminosity.

The fate of different stars depends on their mass, Wheeler said. He defines three categories of high-mass stars that explode as
supernovae:

In the least massive case, around 10 to 20 solar masses, a star collapses in on itself because its iron core cannot hold out against the crushing gravity of the star’s weight. This is the classic “core-collapse supernova” with normal brightness.

The second progenitor category consists of more massive stars, perhaps up to 100 solar masses. This type of star puffs off layers of material before it dies. The interaction between the supernova ejecta and the previously puffed-off material can cause the supernova to brighten to the super-luminous range.

The final category includes the most massive progenitor stars, those more than 100 solar masses. In this case, “the current state of the art predicts that they make matter and antimatter, electron-positron pairs, because they are so hot,” Wheeler said. “That process destabilizes the whole star and it contracts, ignites the thermonuclear fuel, and then explodes, blowing the whole star up.”
These are called “pair-instability” supernovae.

Of the three types of explosions Wheeler describes, the first two would leave behind a stellar remnant in the form of a neutron star or black hole. The third and most massive, though, would explode completely, leaving no remnant.

Though they set a record, the team isn’t finished studying super-luminous supernovae. Their work on understanding SN 2008am might explain the origins of half of the known examples, but as Wheeler said, “to a scientist, the interesting thing is, what’s the other half? ... We want to understand them all before we’re done.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

This press release was adapted from http://mcdonaldobservatory.org/news/releases/2011/0328.html

New Candidate For Coldest ‘Star’

March 23, 2011

Kamuela, HI – There is a new candidate for coldest known star: a brown dwarf with about the same temperature as a hot cup of coffee. That’s cool enough to begin crossing the blurry line between small cold stars and big hot planets.

Brown dwarfs are essentially failed stars: they lack the mass and gravity to trigger the nuclear reactions that make stars shine brightly. The newly discovered brown dwarf, identified as CFBDSIR 1458+10B, is the smaller and dimmer member of a binary brown dwarf system located just 75 light-years from Earth. The pair was discovered by astronomers using the W. M. Keck Observatory and the Canada-France-Hawai’i Telescope (CFHT), both on the summit of Mauna Kea in Hawai’i, following up on earlier work done at European Southern Observatory’s Very Large Telescope in Chile.

The lesser dwarf has a temperature of 370 K, plus or minus 40 K. That translates into about 200 degrees F (100 degrees C) – right around the boiling point of water on Earth’s surface.

“At such temperatures, we expect the brown dwarf has properties that are unique from previously known brown dwarfs and much closer to cold exoplanets, such as the presence of water clouds in its atmosphere,” said Michael Liu of the University of Hawai’i's Institute for Astronomy. “In fact, once we start taking images of gas-giant planets around Sun-like stars in the near-future, I expect that many of them will look like CFBDSIR 1458+10B.”

The researchers are reporting their discovery in an upcoming issue of Astrophysical Journal. Their paper is available online at http://arxiv.org/abs/1103.0014.

CFBDSIR 1458+10B was detected using the Laser Guide Star (LGS) Adaptive Optics system on the Keck II Telescope. Adaptive Optics essentially cancels out much of Earth’s atmospheric interference.

“The binary was resolved with Keck LGS Adaptive Optics imaging, and in fact can only be done with Keck LGS, given the difficulty of the measurement,” said Liu. The double dwarfs were confirmed as a linked pair by two measurements which showed the objects are moving together.

Liu and his colleagues employed the CFHT to determine the distance to the brown dwarf duo – an essential step for interpreting what they observed with the Keck II Telescope. CFHT’s wide-field near-IR camera, WIRCam, allowed astronomers to use the apparent motion of more distant stars behind the brown dwarfs, caused by Earth’s changing position in its orbit around the Sun, to determine the distance to the brown dwarfs.

“This ‘leap forward’ was made possible through the combination of both Keck and CFHT data, taking advantage of the unique instrumentation available on each,” said Trent Dupuy, former University of Hawai’i graduate student, now at the Harvard-Smithsonian Center for Astrophysics, and a coauthor of the paper.

The CFBDSIR 1458+10 system was originally announced last year, but it was believed to be only a single object. Observations with the European Southern Observatory’s Very Large Telescope indicated the combined system had a very low temperature, making it probably the third coolest object to date.

“We were very excited originally to see this object had such a low temperature, but we never guessed that it would turn out to be a binary star and have an even more interesting, even colder companion,” said Philippe Delorme of the University of Grenoble, another coauthor of the paper.

The Spitzer Space Telescope has recently identified two other, very faint objects as other possible contenders for the coolest known objects, though their temperatures are less well-constrained. Future observations will better determine how these objects compare to CFBDSIR 1458+10B.

Liu and his colleagues are planning to observe CFBDSIR 1458+10B in the future to better determine its properties and to begin mapping the binary’s orbit. For the latter, about a decade of monitoring should allow astronomers to even weigh the binary’s mass.

Other coauthors on the paper are Brendan P. Bowler, Loic Albert, Etienne Artigau, Celine Reyle, Thierry Forveille and Xavier Delfosse.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Europa Helps Astronomers Penetrate Jupiter’s Lost Belt

February 9, 2011

Kamuela, HI - The ongoing turmoil inside Jupiter’s missing – and slowly re-emerging – South Equatorial Belt can now be seen in unprecedented detail thanks to the Keck II telescope’s Adaptive Optics system and the cooperation of the icy Jovian moon Europa (more on Jupiter’s missing belt. In this newly released Keck image, the gas giant is shown as it looks in thermal infrared (IR) light, at a wavelength of nearly 5 microns (shown in bright red and yellow), overlaid on a composite image of three shorter, near infrared bands (1.21, 1.58 and 1.65 microns).

“The thermal IR senses breaks in the cloud cover,” said astronomer Mike Wong of the University of California at Berkeley. The thermal IR data is essentially showing heat from Jupiter’s interior being radiated into space. The three other IR bands, in contrast, are reflected sunlight. Put them all together and compare them to visible light images and scientists get a picture of a thinning, breaking layer of high, bright, icy clouds that have obscured the brown-red South Equatorial Belt (SEB) for about a year, making it look like a wide white zone.

“We see wispy cloud-free regions at 5 microns in the SEB,” said Wong, “But they are much less extensive than the near-infrared dark regions surrounding them. The data show that the change from zone-like to belt-like appearance is a complex process that takes place at different speeds in each layer of Jupiter’s atmosphere.”

The four-band infrared image was created using a clever twist on the Keck II Telescope’s Adaptive Optics, which effectively cancels out much of the interference of Earth’s atmosphere. Normally astronomers use a powerful laser to create an artificial guide star. With that they can monitor Earth’s constantly changing atmosphere and cancel out the distortions at a rate of up to 2,000 times per second.

But Jupiter is so bright that it hides the laser guide star. The astronomers needed something much brighter that was also very close to Jupiter in the sky. On November 30, 2010, the icy Jovian moon Europa was positioned just right to serve that purpose, explained Franck Marchis, also of UC Berkeley and the SETI Institute.

Timing observations right so that Europa makes Adaptive Optics possible is no mean feat, according to Marchis, and underscores the technical challenges involved in peering into Jupiter’s clouds. Despite many other researchers watching Jupiter’s changing clouds with other telescopes, none, not even the Hubble Space Telescope, is equipped to peer in the 5 micron band with such high resolution. Marchis, Wong and UC Berkeley astronomer Imke de Pater, are involved in a large monitoring program aimed at following up on these rare and mysterious happenings in Jupiter’s atmosphere. They were assisted in their Keck II observations by W. M. Keck Observatory support astronomer Randy Campbell.

Royal Honor Awarded to Astronomer Richard Ellis

January 20, 2011

Pasadena, CA - Richard Salisbury Ellis, the Steele Family Professor of Astronomy at Caltech, has received the Gold Medal of the Royal Astronomical Society. Awarded annually since 1824, the Gold Medal is the society’s highest honor and one of the premier prizes in astronomy. Ellis joins a long list of distinguished recipients, including several from Caltech: Don Anderson, Peter Goldreich, Gerald Wasserburg, Maarten Schmidt, Fritz Zwicky, Jesse Greenstein, Ira Bowen, and George Ellery Hale.

According to the London-based society’s award citation, “[Ellis] has been one of the most influential British astronomers in the past thirty years,” and the Gold Medal recognizes his “outstanding personal research achievements and his leadership in astronomy.” Ellis’s research focuses on the large-scale distribution of matter in the universe; the cosmic expansion history; and the evolution of galaxies, through detailed studies of nearby systems and the exploration of the very earliest objects. After Ellis joined Caltech’s faculty in 1999, the latter observations were accomplished in large part at the Keck Observatory.

“We are very proud that Richard continues the long tradition of outstanding achievement in astronomy at Caltech,” says Tom Soifer, professor of physics and chair of the Division of Physics, Mathematics and Astronomy, and a director of the W. M. Keck Observatory.

As a scientific mentor, Ellis has supervised 30 PhD students; 28 are still active in academic research. He served on the board of the Keck Observatory and as Director of Palomar Observatory (now Caltech Optical Observatories) from 2000 to 2005 and has played an important role in building the science case and partnership for the upcoming Thirty Meter Telescope.

He has received several other honors, including sharing the Peter and Patricia Gruber Foundation’s Cosmology Prize for his part in the discovery of the accelerating universe and the Royal Astronomical Society’s Group Achievement Award for his leadership in the 2-degree-Field Galaxy Redshift Survey, one of the largest astronomical surveys ever performed. In 2008, Ellis was made a Commander of the British Empire by Queen Elizabeth II for services to international science, and he is a fellow of the Royal Society, the American Association for the Advancement of Science, and the Institute of Physics.

Born in Wales, Ellis received his undergraduate degree from University College London and his Ph.D. from Oxford University. Before becoming a professor at Caltech in 1999, he was a distinguished member of the astronomical community in the United Kingdom where he served as the prestigious Plumian Professor of Astronomy and Experimental Philosophy at Cambridge.

Astronomers Discover New Clues to Galaxy Evolution

January 12, 2011

Seattle, WA - Astronomers at the California Institute of Technology (Caltech), University of Illinois at Urbana-Champaign (UIUC), and University of Hawai’i (UH) have discovered 16 close-knit pairs of supermassive black holes in merging galaxies. The research findings, based on observations done at the W. M. Keck Observatory on Mauna Kea, were presented in Seattle this week at the 217th meeting of the American Astronomical Society.The black-hole pairs, also called binaries, are about a hundred to a thousand times closer together than most that have been observed before, providing astronomers a glimpse into how these behemoths and their host galaxies merge—a crucial part of understanding the evolution of the universe. Although few similarly close pairs have been seen previously, this is the largest population of such objects observed as the result of a systematic search.

“This is a very nice confirmation of theoretical predictions,” says S. George Djorgovski, Professor of Astronomy at Caltech. “These close pairs are a missing link between the wide binary systems seen previously and the merging black-hole pairs at even smaller separations that we believe must be there.”

As the universe has evolved, galaxies have collided and merged to form larger ones. Nearly every one—or perhaps all—of these large galaxies contains a giant black hole at its center, with a mass millions—or even billions—of times higher than the sun’s. Material such as interstellar gas falls into the black hole, producing enough energy to outshine galaxies composed of a hundred billion stars. The hot gas and black hole form an active galactic nucleus, the brightest and most distant of which are called quasars. The prodigious energy output of active galactic nuclei can affect the evolution of galaxies themselves.

While galaxies merge, so should their central black holes, producing an even more massive black hole in the nucleus of the resulting galaxy. Such collisions are expected to generate bursts of gravitational waves, which have yet to be detected. Some merging galaxies should contain pairs of active nuclei, indicating the presence of supermassive black holes on their way to coalescing. Until now, astronomers have generally observed only widely separated pairs—binary quasars—which are typically hundreds of thousands of light-years apart.

“If our understanding of structure formation in the universe is correct, closer pairs of active nuclei must exist,” adds Adam Myers, a research scientist at UIUC and one of the coauthors of the research that has been submitted for publication in the Astrophysical Journal. “However, they would be hard to discern in typical images blurred by Earth’s atmosphere.”

The solution was to use Laser Guide Star Adaptive Optics, a technique that enables astronomers to remove the atmospheric blur and capture images as sharp as those taken from space. One such system is deployed on the W. M. Keck Observatory’s 10-meter telescopes on Mauna Kea.

NASA Study Distinguishes Most Distant Galaxy Cluster

January 12, 2011

Kamuela, HI - Astronomers have uncovered a burgeoning galactic metropolis, the most distant known in the early universe. This ancient collection of galaxies presumably grew into a modern galaxy cluster similar to the massive ones seen today.

The developing cluster, named COSMOS-AzTEC3, was discovered and characterized using multiple telescopes, including NASA’s Spitzer, Chandra and Hubble space telescopes, and the ground-based W. M. Keck Observatory, of which NASA is a one-sixth partner, and Japan’s Subaru Telescope.

“This exciting discovery showcases the exceptional science made possible through collaboration among NASA projects and our international partners,” said Jon Morse, NASA’s
Astrophysics Division director at NASA Headquarters in Washington.

Scientists refer to this growing lump of galaxies as a proto-cluster. COSMOS-AzTEC3 is the most distant massive proto-cluster known, and also one of the youngest, because it is being seen when the universe itself was young. The cluster is roughly 12.6 billion light-years away from Earth. Our universe is estimated to be 13.7 billion years old. Previously, more mature versions of these clusters had been spotted at 10 billion light-years away.

The astronomers also found that this cluster is buzzing with extreme bursts of star formation and one enormous feeding black hole.

“We think the starbursts and black holes are the seeds of the cluster,” said Peter Capak of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena. “These seeds will eventually grow into a giant, central galaxy that will dominate the cluster—a trait found in modern-day galaxy clusters.” Capak is first author of a paper appearing in the Jan. 13 issue of the journal Nature.

Most galaxies in the universe are bound together into clusters that dot the cosmic landscape like urban sprawls, usually centered around one old, monstrous galaxy containing a massive black hole. Astronomers thought that primitive versions of these clusters, still forming and clumping together, should exist in the early universe. But locating one proved difficult—until now.

Capak and his colleagues first used the Chandra X-ray Observatory and the United Kingdom’s James Clerk Maxwell Telescope on Mauna Kea, Hawai’i, to search for the black holes and bursts of star formation needed to form the massive galaxies at the centers of modern galaxy cities. The astronomers then used Hubble and the Subaru telescopes to estimate the distances to these objects, and look for higher densities of galaxies around them. Finally, the Keck II telescope was used to confirm that these galaxies were at the same distance and part of the same galactic sprawl.

Once the scientists found this lumping of galaxies, they measured the combined mass with the help of Spitzer. At this distance the optical light from stars is shifted, or stretched, to infrared wavelengths that can only be observed in outer space by Spitzer. The lump sum of the mass turned out to be a minimum of 400 billion suns—enough to indicate that the astronomers had indeed uncovered a massive proto-cluster. The Spitzer observations also helped confirm a massive galaxy at the center of the cluster was forming stars at an impressive rate.

Chandra X-ray observations were used to find and characterize the whopping black hole with a mass of more than 30 million suns. Massive black holes are common in present-day galaxy clusters, but this is the first time a feeding black hole of this heft has been linked to a cluster that is so young.

Finally, the Institut de Radioastronomie Millimétrique’s interferometer telescope in France and 30-meter telescope in Spain, along with the National Radio Astronomy Observatory’s Very Large Array telescope in New Mexico, measured the amount of gas, or fuel for future star formation, in the cluster. The results indicate the cluster will keep growing into a modern city of galaxies.

“It really did take a village of telescopes to nail this cluster,” said Capak. “Observations across the electromagnetic spectrum, from X-ray to millimeter wavelengths, were all critical in providing a comprehensive view of the cluster’s many facets.”

COSMOS-AzTEC3, located in the constellation Sextans, is named after the region where it was found, called COSMOS after the Cosmic Evolution Survey. AzTEC is the name of the camera used on the James Clerk Maxwell Telescope—this camera is now on its way to the Large Millimeter Telescope located in Mexico’s Puebla state.

Keck Observatory pictures show fourth planet in giant solar system

December 8, 2010

Kamuela, HI - Astronomers announced the discovery of a fourth giant planet joining three others orbiting a nearby star with information that challenges our current understanding of planet formation. The dusty young star named HR8799, located 129 light years away, was first recognized in 2008 when these same astronomers presented the first-ever images of a planetary system orbiting a star other than our sun.

Now, a research team from Lawrence Livermore National Laboratory (LLNL), National Research Council of Canada (NRC), the University of California Los Angeles, (UCLA) and Lowell Observatory has discovered a fourth planet that is about 7 times the mass of Jupiter – similar to the other three. Using high-contrast, near infrared adaptive optics on the Keck II telescope in Hawaii, the astronomers imaged the fourth planet (dubbed HR8799e) in 2009 and confirmed its existence and orbit in 2010. The research appears in the Dec. 8 edition of the journal, Nature.

“The images of this new inner planet in the system is the culmination of 10 years worth of innovations, making steady progress to optimize every observation and analysis step to allow the detection of planets located ever closer to their stars,” said Christian Marois, a former LLNL postdoc now at NRC, and first author of the new paper.

If this newly discovered planet was located in orbit around our sun, it would lie between Saturn and Uranus. This giant version of our solar system is young at about 30 million years old compared to our system, which is about 4.6 billion years old.

Though the system is very much like our own, in other ways, it is much more extreme than our own – the combined mass of the four giant planets may be 20 times higher, and the asteroid and comet belts are dense and turbulent. In fact, the massive planets’ pull on each other gravitationally, and the system may be on the verge of falling apart.

This team of scientists simulated millions of years of evolution of the system, and showed that to have survived this long, the three inner planets may have to orbit like clockwork, with the new planet going around the star exactly four times while the second planet finishes two orbits in the time it takes the outer planet to complete one. This behavior was first seen in the moons of Jupiter but has never before been seen on this scale.

Studying the planet’s orbits also will help estimate their masses. “Our simulations show that if the objects were not planets, but supermassive ‘brown dwarfs’, the system would have fallen apart already,” said Quinn Konopacky, a postdoctoral researcher at LLNL’s Institute of Geophysics and Planetary Physics and a key author of the paper. “The implication is that we have truly found a unique new system of planets.” (Brown dwarfs are “failed stars”, too low in mass to sustain stable hydrogen fusion but larger than planets.) “We don’t yet know if the system will last for billions of years, or fall apart in a few million more. As astronomers carefully follow the HR 8799 planets during the coming decades, the question of just how stable their orbits are could become much clearer.”

The origin of these four giant planets remains a puzzle. It neither follows the “core accretion” model, in which planets form gradually close to stars where the dust and gas are thick or the “disk fragmentation” model in which a turbulent planet-forming disk rapidly cools and collapses out at its edges. Bruce Macintosh, a senior scientist at LLNL and the principal investigator for the Keck Observatory program, said: “There’s no simple model that can make all four planets at their current location. It’s a challenge for our theoretical colleagues.”

Previous observations had shown evidence for a dusty asteroid belt orbiting closer to the star – the new planet’s gravity helps account for the location of those asteroids, confining their orbits just like Jupiter does in our solar system. “Besides having four giant planets, both systems contain also two so-called “debris belts” composed of small rocky and/or icy objects along with lots of tiny dust particles, similar to the asteroid and Kuiper comet belts of our solar system”, noted co-author Ben Zuckerman, a professor of physics and astronomy at UCLA.

“Images like these bring the exoplanet field into the era of characterization. Astronomers can now directly examine the atmospheric properties of four giant planets orbiting another star that are all the same young age and that formed from the same building materials.” said Travis Barman, a Lowell Observatory exoplanet theorist and co-author of the current paper.

“I think there’s a very high probability that there are more planets in the system that we can’t detect yet,” Macintosh said. “One of the things that distinguishes this system from most of the extrasolar planets that are already known is that HR8799 has its giant planets in the outer parts - like our solar system does - and so has ‘room’ for smaller terrestrial planets – far beyond our current ability to see – in the inner parts.”

“It’s amazing how far we’ve come in a few years,” Macintosh said. “In 2007, when we first saw the system, we could barely see two planets out past the equivalent of Pluto’s orbit. Now we’re imaging a fourth planet almost where Saturn is on our solar system. It’s another step to the ultimate goal – still more than a decade away – of a picture showing another planet like Earth.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Discovery Triples Total Number of Stars in Universe

December 1, 2010

Kamuela, HI - Astronomers have discovered that small, dim stars known as red dwarfs are much more prolific than previously thought—so much so that the total number of stars in the universe is likely three times bigger than realized.

Because red dwarfs are relatively small and dim compared to stars like our Sun, astronomers hadn’t been able to detect them in galaxies other than our own Milky Way and its nearest neighbors before now. As such, they did not know how much of the total stellar population of the universe is made up of red dwarfs.

Now astronomers have used powerful instruments on the W. M. Keck Observatory in Hawaii to detect the faint signature of red dwarfs in eight massive, relatively nearby galaxies called elliptical galaxies, which are located between about 50 million and 300 million light years away. They discovered that the red dwarfs, which are only between 10 and 20 percent as massive as the Sun, were much more bountiful than expected.

“This important study, which uses information at the red end of the optical spectrum, was aided by advances in detector technology that have been implemented at Keck,” said Keck Observatory Director Taft Armandroff.

“No one knew how many of these stars there were,” said Pieter van Dokkum, a Yale University astronomer who led the research, which is described in Nature’s Dec.1 Advanced Online Publication. “Different theoretical models predicted a wide range of possibilities, so this answers a longstanding question about just how abundant these stars are.”

The team discovered that there are about 20 times more red dwarfs in elliptical galaxies than in the Milky Way, said Charlie Conroy of the Harvard-Smithsonian Center for Astrophysics, who was also involved in the research.

“We usually assume other galaxies look like our own. But this suggests other conditions are possible in other galaxies,” Conroy said. “So this discovery could have a major impact on our understanding of galaxy formation and evolution.”

For instance, Conroy said, galaxies might contain less dark matter—a mysterious substance that has mass but cannot be directly observed—than previous measurements of their masses might have indicated. Instead, the abundant red dwarfs could contribute more mass than realized.

In addition to boosting the total number of stars in the universe, the discovery also increases the number of planets orbiting those stars, which in turn elevates the number of planets that might harbor life, van Dokkum said. In fact, a recently discovered exoplanet that astronomers believe could potentially support life orbits a red dwarf star, called Gliese 581.

“There are possibly trillions of Earths orbiting these stars,” van Dokkum said, adding that the red dwarfs they discovered, which are typically more than 10 billion years old, have been around long enough for complex life to evolve. “It’s one reason why people are interested in this type of star.”

Observations of Jupiter reveal rare signatures of weather

November 29, 2010

Kamuela, HI, - One of Jupiter’s dark brown stripes that faded out last spring is regaining its color, providing an unprecedented opportunity for astronomers to observe a rare and mysterious phenomenon caused by the planet’s winds and cloud chemistry.
Earlier this year, amateur astronomers noticed that the long-standing stripe, known as the South Equatorial Belt (SEB), just south of Jupiter’s equator, had turned white. In early November, amateur astronomer Christopher Go of Cebu City in the Philippines observed a prominent bright spot in the unusually whitened belt, piquing the interest of professional and amateur astronomers around the world.
After follow-up observations with NASA’s Infrared Telescope Facility (IRTF), the 10-meter Keck II telescope and the 8-meter Gemini telescope, all on Mauna Kea in Hawaii, scientists at the University of California, Berkeley, and elsewhere now believe the stripe is making a comeback.
Astronomers announced first-glimpse images of the reappearing stripe Nov. 24.
“The reason Jupiter seemed to ‘lose’ this band — camouflaging itself among the surrounding white bands — is that the usual downwelling winds that are dry and keep the region clear of clouds died down,” said Glenn Orton, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “One of the things we were looking for in the infrared was evidence that the darker material appearing in visible light was actually the start of clearing in the cloud deck, and that is precisely what we saw.”
This white cloud deck is made up of white ammonia ice. When the white clouds float at a higher altitude, they obscure the view of the lower brown clouds. Every few decades or so, the South Equatorial Belt turns completely white for perhaps one to three years, an event that has puzzled scientists for decades. This extreme change in appearance has only been seen with the South Equatorial Belt, making it unique to Jupiter and to the entire solar system.
The bright storm that Go observed in the faded belt was quite unusual, said Imke de Pater, UC Berkeley professor of astronomy.
“At infrared wavelengths, images in reflected sunlight show that the spot is a tremendously energetic ‘outburst,’ a vigorous storm that reaches extreme high altitudes,” de Pater said. “The storms are surrounded by darker areas, bluish-grey in the visible, indicative of ‘clearings’ in the cloud deck.”
To confirm the presence of such clearings, the team obtained data at longer wavelengths (5 micron) sensitive to thermal emission from Jupiter’s deep atmosphere. These data confirm that the visibly dark material indeed is being seen through holes in the cloud deck, “perhaps signaling the start of the SEB revival,” added Glenn Orton.
The white band wasn’t the only change on the big, gaseous planet. At the same time, Jupiter’s Great Red Spot became a darker red color. Orton said the color of the spot — a giant storm on Jupiter that is three times the size of Earth and a century or more old — will likely brighten a bit again as the South Equatorial Belt makes its comeback.
The South Equatorial Belt underwent a slight brightening, known as a “fade,” just as NASA’s New Horizons spacecraft was flying by on its way to Pluto in 2007. Then there was a rapid “revival” of its usual dark color three to four months later. The last full fade and revival was a double-header event, starting with a fade in 1989, revival in 1990, then another fade and revival in 1993. Similar events have been captured visually and photographically back to the early 20th century, and they are likely to be a long-term phenomenon in Jupiter’s atmosphere.

Scientists are particularly interested in this event because it’s the first time they’ve been able to use modern instruments to determine the details of the chemical and dynamical changes of this phenomenon.
“These observations may help to unravel the mystery of why this transition occurs, and may allow us to understand the longevity of Jupiter’s belt/zone structure,” added Leigh Fletcher, a scientist at Oxford University in England.
The event also signifies another close collaboration between professional and amateur astronomers. The amateurs, located worldwide, are often well equipped with instrumentation and are able to track the rapid developments of planets in the solar system. These amateurs are collaborating with professionals to further study the changes that are of great value to scientists and researchers everywhere.
“I was fortunate to catch the outburst,” Go said. “I had a meeting that evening, and it went late. I caught the outburst just in time as it was rising. Had I imaged earlier, I would not have caught it.”
Go witnessed the disappearance of the stripe earlier this year, and in 2007 he was the first to catch the stripe’s return. “I was able to catch it early this time around because I knew exactly what to look for,” he said.
Since the discovery of the first spot, there have been several more outbreaks of varying strengths. The SEB revival is happening fast, with violent eruptions, de Pater said.
Observing this event carefully may help to refine the scientific questions that will be posed by NASA’s Juno spacecraft, due to arrive at Jupiter in 2016, and a larger mission to orbit Jupiter and explore its satellite Europa after 2020.
The observations were conducted by a large team of observers around the world. At UC Berkeley, the following researchers are involved: Imke de Pater, Michael Wong, James Graham, Shelley Wright and Franck Marchis. More observations at near- and mid-infrared wavelengths are planned for the coming weeks.

Study says solar systems like ours may be common

October 28, 2010

Kamuela, HI, - Nearly one in four stars like the Sun could have Earth-size planets, according to observations of nearby solar-mass stars made with the Keck telescopes in Hawai’i.

UC Berkeley astronomers Andrew Howard and Geoffrey Marcy chose 166 G and K stars within 80 light years of Earth and observed them for five years in order to determine the number, mass and orbital distance of any of the stars’ planets. The Sun is the best known of the G stars, which are yellow, while K-type dwarfs are slightly smaller, orange-red stars.

The researchers found increasing numbers of smaller planets, down to the smallest size detectable today – planets called super-Earths, about three times the mass of Earth. The census, funded by NASA and the University of California, is the most extensive of its kind to date.

“Of about 100 typical Sun-like stars, one or two have planets the size of Jupiter, roughly six have a planet the size of Neptune, and about 12 have super-Earths between three and 10 Earth masses,” said Howard, a research astronomer in UC Berkeley’s Department of Astronomy and at the Space Sciences Laboratory. “If we extrapolate down to Earth-size planets – between one-half and two times the mass of Earth – we predict that you’d find about 23 for every 100 stars.”

“This is the first estimate based on actual measurements of the fraction of stars that have Earth-size planets,” said Marcy, UC Berkeley professor of astronomy. Previous studies have estimated the proportion of Jupiter and Saturn-size exoplanets, but never down to Neptune’s and super-Earths, enabling an extrapolation to Earth-size planets.

“What this means,” Howard added, “is that, as NASA develops new techniques over the next decade to find truly Earth-size planets, it won’t have to look too far.”

Because the researchers detected only close-in planets, there could be even more Earth-size planets at greater distances, including within the habitable zone located at about the same distance as Earth is from the Sun. The habitable, or “Goldilocks,” zone is the distance from a star neither too hot nor too cold to allow the presence of liquid water.

The researchers’ results conflict with current models of planet formation and migration, Marcy noted. After their birth in a protoplanetary disk, planets had been thought to spiral inward because of interactions with the gas in the disk. Such models predict a “planet desert” in the inner region of solar systems. The new study finds a surplus of close-in, small planets. “These results will transform astronomers’ views of how planets form,” Marcy said.

Howard and Marcy report their results in the Oct. 29 issue of the journal Science.

The astronomers used the 10-meter Keck telescopes in Hawaii to measure the minute wobble of each star. Current techniques allow detection of planets massive enough and near enough to their stars to cause a wobble of about 1 meter per second. That means they saw only massive, Jupiter-like gas giants up to three times the mass of Jupiter (1,000 times Earth’s mass) orbiting as far as one-quarter of an astronomical unit (AU) from the star, or smaller, closer super-Earths and Neptune-like planets (15-30 times the mass of the earth). An AU is 93 million miles, the average distance between Earth and the Sun.

Only 22 of the stars had detectable planets – 33 planets in all – within this range of masses and orbital distances. After accounting statistically for the fact that some stars were observed more often than others, the researchers estimated that about 1.6 percent of the sun-like stars in their sample had Jupiter-size planets and 12 percent had super-Earths (3-10 Earth masses). If the trend of increasing numbers of smaller planets continues, they concluded, 23 percent of the stars would have Earth-size planets.

Based on these statistics, Howard and Marcy, who is a member of NASA’s Kepler mission to survey 156,000 faint stars in search of transiting planets, estimate that the telescope will detect 120-260 “plausibly terrestrial worlds” orbiting some 10,000 nearby G and K dwarf stars with orbital periods less than 50 days.

“One of astronomy’s goals is to find eta-Earth (ηEarth), the fraction of sun-like stars that have an earth,” Howard said. “This is a first estimate, and the real number could be one in eight instead of one in four. But it’s not one in 100, which is glorious news.”

“This study represents a breakthrough in our understanding of the frequency and distribution of planets,” said Taft Armandroff, Director of Keck Observatory. “The conclusion that Earth-mass planets are common reflects a major investment in observing time along with refinements in observing techniques developed by Keck Observatory and our planet-hunting community.”

Twelve possible planets also were detected, but they need further confirmation, Marcy said. If these candidate planets are included in the count, the team detected a total of 45 planets around 32 stars.

Other coauthors of the paper are John Asher Johnson of the California Institute of Technology (Caltech), Debra A. Fischer of Yale University, Jason T. Wright of Pennsylvania State University, Howard Isaacson of UC Berkeley, Jeff A. Valenti and Jay Anderson of the Space Telescope Science Institute in Baltimore, Md., Doug N. C. Lin of the UC Observatories/Lick Observatory and UC Santa Cruz, and Shigeru Ida of the Tokyo Institute of Technology in Japan.

Ground-Based Images of Asteroid Lutetia Complement Spacecraft Flyby

October 7, 2010

Kamuela, HI, - The European Space Agency (ESA) Rosetta spacecraft recently beamed back to Earth a dramatic set of close-up images as it flew past the asteroid Lutetia, on its way to a comet rendezvous in 2014. But even before Rosetta made its close encounter with the 100-kilometer sized asteroid, astronomers using three of the world’s largest telescopes, including the W. M. Keck Observatory, were busy making their own assessment of the asteroid’s shape and size, as well as searching for its satellites. Their pre-flyby images are being compared this week with those from Rosetta at a meeting of the Division for Planetary Sciences of the American Astronomical Society in Pasadena, California, revealing that the ground-based images are amazingly accurate.

These telescopes all use adaptive optics (AO), which removes the blurring caused by the Earth’s atmosphere. Using something like a fun-house mirror in reverse, AO allows clear pictures to be made, from Earth’s surface, of distant astronomical objects that were impossible to see previously. “Adaptive optics has set in motion an astronomical revolution, bringing new worlds into better view, ranging from asteroids that were previously unresolved pinpoints of light, to the discovery of new planets in other solar systems,” said Dr. William Merline of Southwest Research Institute (SwRI) in Boulder, Colorado, lead scientist of the international team that made the observations, funded by NASA and the National Science Foundation. Two of the telescopes are atop Mauna Kea in Hawaii: the W.M. Keck telescope with its 10-meter mirror and the Gemini telescope, equipped with an 8-meter mirror. The 8-meter Very Large Telescope (VLT) of the European Southern Observatory in Chile was also used.

“We carefully evaluated the size and shape of Lutetia, and pinned down the orientation of its spin pole using telescopes on Earth, prior to the flyby,” reported Dr. Jack Drummond, an astronomer at Starfire Optical Range in Albuquerque, New Mexico, where AO was first developed in the early 1990s and can be considered the cradle of adaptive optics. Drummond is an expert in turning AO images into models of asteroids, detailing their shapes and sizes. He is the lead author on the first of two papers predicting the appearance of Lutetia, which are now in press in the journal Astronomy and Astrophysics. Drummond adds, “after the many years developing these techniques at Starfire, it is gratifying to see how well they work when put to this kind of test.”

Rosetta’s Lutetia encounter provided a rare chance to combine the strengths of spacecraft and ground-based approaches to understand the complex shapes and elusive sizes of asteroids. For decades, astronomers watched Lutetia change brightness as it rotates. Before adaptive optics, such “lightcurve” studies were the only way astronomers could infer the shape of a body like Lutetia. “A sphere will have a flat lightcurve, an egg will have a lightcurve that goes up and down smoothly like an ocean swell, but an irregular potato-shape will look like your EKG on a bad day!”, says Dr. Al Conrad of Keck Observatory, where many of the observations were made.

While lightcurves provide approximate shape, they cannot provide fine detail nor absolute scale. “AO has dramatically improved our ability to determine asteroid shapes from the ground by providing both of these missing ingredients,” said team member Dr. Benoit Carry of Paris Observatory, who led the efforts to produce the “shape model”, derived by combining AO images with decades of lightcurve observations taken on smaller telescopes. “We dubbed this new technique KOALA, for Knitted Occultation Adaptive Optics, and Lightcurve Analysis. With it, we can make much improved use of our own data and of previous studies,” adds Carry, who leads the second paper and worked to develop KOALA in collaboration with Dr. Mikko Kaasalainen of Tampere University, Finland. The results were provided to the Rosetta mission teams ahead of the flyby to assist in planning.

Such ground-based imaging can help prepare for spacecraft flybys in other ways as well. “We determined that the spin pole of the asteroid was highly inclined, and almost in its orbital plane, much like that of Uranus,” says Carry. “We predicted that Rosetta would see only the northern hemisphere and that the southern hemisphere would be dark and cold,” he said --- predictions borne out by the flyby data.

“This encounter enables us to verify, validate, and calibrate our method of combining AO data with lightcurve studies,” noted Merline. “Our goal is to apply this technique to many other asteroids to find their sizes and shapes. The validation from these flyby images gives us confidence that we can do so. We can observe about 200 asteroids in this manner now, and that number will increase as larger telescopes are built,” he adds.

“The tremendous power of the Keck telescope, when coupled with AO, is demonstrated superbly in the Lutetia data,” says Conrad. Because asteroids have no active geology, such as volcanoes or tectonics, their shapes result from collision with other, smaller, asteroids. “Details of shape, such as flat facets or apparent concavities, help reveal the history of asteroid collisions,” he adds. The importance of collisions can be seen in the crater-marked surface of the Moon, reminding us that asteroids continue to pose a threat to Earth.

The AO images from large telescopes, used in concert with lightcurves and the spacecraft images, go beyond validation, however. By combining all data, Lutetia’s shape could be accurately determined, allowing astronomers to compute its volume. Moreover, measurements of the gravitational tug from Lutetia on the spacecraft as it flew past the asteroid will yield a very accurate mass. Mass and volume, taken together, will provide the density of Lutetia. Density is the concept of how much something weighs for its size. For example, two wrapped birthday gifts of the same size, one of Styrofoam™ and one of lead, would invoke very different speculations from a recipient. Asteroid compositions could potentially span the full range from ice to rock to iron. Different compositions of an asteroid could be distinguished by different densities. Astronomers use this “birthday present” approach, combined with information from studies of the brightness and color of the surface, to infer the type of rock (or ice or metal) that makes up an asteroid.

Lutetia was first categorized as an M-type asteroid in the 1970s by team member Dr. Clark Chapman, also of SwRI. “Some people think that M-type asteroids must be metallic, but it has always been known that some might be rocky, like the so-called enstatite chondrite meterorites,” says Chapman. “While Lutetia is not metallic, its composition is still a mystery and it may even be unlike anything we have in our meteorite collections. We hope that getting an accurate density will help us answer this question,” he says. The spacecraft data will be combined with past and future ground-based observations, and the secret of Lutetia’s composition may be revealed in
the coming months.

In addition to studying its size and shape, the scientists also searched for satellites of Lutetia, but none were found. “We wanted to know if satellites were present because they would at the same time provide new objects for study during the flyby, but would also pose a risk to the spacecraft that could be avoided with prior knowledge,” says Merline.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a private 501(c) 3 organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Keck Observatory discovers the first Goldilocks exoplanet

September 29, 2010

Kamuela, HI, - A team of planet-hunting astronomers, utilizing the HIRES spectrometer on the W.M. Keck Observatory’s Keck I Telescope, has announced the discovery of an Earth-sized planet orbiting a nearby star. The new planet, known as Gliese 581g, is at a distance that places it squarely in the middle of the star’s “habitable zone” where liquid water could exist on the planet’s surface. If confirmed, this would be the most Earth-like exoplanet and the first bona fide potentially habitable one yet discovered.

The discovery by the team, led by astronomers at the University of California, Santa Cruz, and the Carnegie Institution of Washington D.C., is based on 11 years of observations made at the Keck Observatory atop Mauna Kea mountain on the Big Island of Hawaii. “Our findings offer a very compelling case for a potentially habitable planet,” said Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz. “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.”

“Advanced techniques combined with old-fashioned ground-based telescopes continue to lead the exoplanet revolution,” added Paul Butler of the Carnegie Institution. “Our ability to find potentially habitable worlds is now limited only by our telescope time.”

Vogt and Butler lead the Lick-Carnegie Exoplanet Survey. The team’s new findings are reported in a paper to be published in the Astrophysical Journal and posted online at arXiv.org. Coauthors include UCSC associate research scientist Eugenio Rivera; associate astronomer Nader Haghighipour of the University of Hawaii-Manoa; and research scientists Gregory Henry and Michael Williamson of Tennessee State University.

The paper reports the discovery of not one but two new planets around the nearby red dwarf star known as Gliese 581. This brings to six the number of known planets around this star, the most yet discovered in a planetary system other than our own solar system. Like our solar system, the planets around Gliese 581 have nearly circular orbits. Gliese 581g has a mass 3 to 4 times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, according to Vogt.

Keck’s HIRES spectrometer allows precise measurements of a star’s radial velocity (its motion along the line of sight from Earth), which can reveal the presence of planets. The gravitational tug of an orbiting planet causes periodic changes in the radial velocity of the host star. Multiple planets induce complex wobbles in the star’s motion, and astronomers use sophisticated analyses to detect planets and determine their orbits and masses.

“It’s really hard to detect a planet like this,” Vogt said. “Every time we measure the radial velocity, that’s an evening on the telescope, and it took more than 200 observations with a precision of about 1.6 meters per second to detect this planet.”

To get that many radial velocity measurements (238 in total), Vogt’s team combined their HIRES observations with published data from another group led by the Geneva Observatory (HARPS, the High Accuracy Radial velocity Planetary Search project).

In addition to the radial velocity observations, coauthors Henry and Williamson made precise night-to-night brightness measurements of the star with one of Tennessee State University’s robotic telescopes. “Our brightness measurements verify that the radial velocity variations are caused by the new orbiting planet and not by any process within the star itself,” Henry said.

The researchers also explored the implications of this discovery with respect to the number of stars that are likely to have at least one potentially habitable planet. Given the relatively small number of stars that have been carefully monitored by planet hunters, this discovery has come surprisingly soon.

“If these are rare, we shouldn’t have found one so quickly and so nearby,” Vogt said. “The number of systems with potentially habitable planets is probably on the order of ten or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that’s a large number. There could be tens of billions of these systems in our galaxy.”

Gliese 581, located 20 light years away from Earth in the constellation Libra, has a somewhat checkered history of habitable-planet claims. Two previously detected planets in the system lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly discovered planet g, however, lies right in the middle of the habitable zone.

“It’s the Goldilocks planet,” Vogt said. “That’s a well-worn analogy, but in this case it fits. We had planets on both sides of the habitable zone—one too hot and one too cold—and now we have one in the middle that’s just right.”

The planet is tidally locked to the star, meaning that one side is always facing the star and basking in perpetual daylight, while the side facing away from the star is in perpetual darkness. One effect of this is to stabilize the planet’s surface climates, according to Vogt. The most habitable zone on the planet’s surface would be the line between shadow and light (known as the “terminator”), with surface temperatures decreasing toward the dark side and increasing toward the light side. “Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude,” Vogt said.

The researchers estimate that the average surface temperature of the planet is between -24 and 10 degrees Fahrenheit (-31 to -12 degrees Celsius). Actual temperatures would range from blazing hot on the side facing the star to freezing cold on the dark side.

If Gliese 581g has a rocky composition similar to the Earth’s, its diameter would be about 1.2 to 1.4 times that of the Earth. The surface gravity would be about the same or slightly higher than Earth’s, so that a person could easily walk upright on the planet, Vogt said.

This research was supported by grants from the National Science Foundation and NASA.

Spectrum of young extrasolar planet yields surprising results

August 30, 2010

Kamuela, HI - Astronomers at the University of Hawaii have measured the temperature of a young gas-giant planet around another star using the W. M. Keck Observatory, and the results are puzzling. They have found that its atmosphere is unlike that of any previously studied extrasolar planet.

By obtaining a spectrum of its emitted light, the astronomers determined the temperature of the planet. As a result, they found that current theoretical models of gas-giant planets did a poor job of explaining all the data. The team suspects that the reason is dust in the planet’s atmosphere. Models with normal amounts of dust do not resemble this planet, but models with exceptionally thick dust clouds do a much better job. It therefore appears that young gas-giant planets are extremely cloudy.

“We are at a point where not only can we directly image planets around other stars, but we can begin to study the properties of their atmospheres in detail. Direct spectroscopy of exoplanets is the future of this field,” said Mr. Brendan Bowler, a graduate student at the University of Hawaii and the lead author of the study.

The planet, known as HR 8799 b, is one of three gas-giant planets orbiting the star HR 8799, located 130 light-years away from Earth in the constellation Pegasus. (For reference, the distance to the nearest nighttime star from Earth is about four light-years.) HR 8799 b is the lowest-mass planet around the star, about seven times the mass of Jupiter. This multiplanet system was discovered by direct imaging in 2008, and now, only a year and a half later, astronomers have obtained a spectrum of one of its planets. The spectrum of a planet contains much more information than a single image: it can reveal the temperature, chemical composition, and cloud properties of the planet.

The technique the team used to determine the planet’s temperature relies on the chemistry of the planet’s atmosphere. Specifically, the presence or absence of gaseous methane can be used as a thermometer. The team found that HR 8799 b shows little or no methane in its atmosphere. Based on their spectrum and previously obtained images of the planet, and by comparing the observations to theoretical models of low-temperature atmospheres, they estimate the coolest possible temperature for the planet is about 1200 Kelvin (about 1,700 degrees Fahrenheit).

The models, however, did a poor job of reproducing all the data. Current theoretical models predict HR 8799 b should be about 400 Kelvin cooler than they measured, based on the age of the planet and the amount of energy it is currently emitting. The team suspects the discrepancy arises because the planet is much more dusty and cloudy than expected by current models.

“Direct studies of extrasolar planets are just in their infancy. But even at this early stage, we are learning they are a different beast than objects we have known about previously,” said University of Hawaii astronomy professor Michael Liu, coauthor of the study.

The planets around HR 8799 are incredibly faint, about 100,000 times dimmer than their parent star. To obtain the spectrum of HR 8799 b, the team relied on the adaptive optics system of the Keck II Telescope to make an ultra-sharp image of the star for many hours. Then they used the Keck facility instrument called OSIRIS, a special kind of spectrograph, to precisely separate the spectrum of the planet from the light of its parent star.

“Adaptive optics systems on Keck and other large ground-based telescopes make sharper images than even the Hubble Space Telescope. With adaptive optics, we are learning an incredible amount about objects that are smaller than the lowest-mass stars and larger than the most massive gas-giant planets in our solar system,” said Mr. Trent Dupuy, a University of Hawaii graduate student and co-author on the study. Dr. Michael Cushing of the Jet Propulsion Laboratory was also a member of the team announcing these results.

Although over 500 planets have been discovered around other stars, only six planets have been directly imaged. Three of these are around HR 8799 and were discovered in 2008 by Christian Marois of Canada’s National Research Council and collaborators. When it was announced, the discovery represented one of the first direct images of light emitted from extrasolar planets.

A paper describing the study will be published in the Astrophysical Journal later this year. A copy is available here http://arxiv.org/abs/1008.4582.

NSF Awards $1.72 Million to Improve the Keck I Laser Guide Star Adaptive Optics System

August 11, 2010

Kamuela, HI— The W. M. Keck Observatory has received a $1.72 million grant from the National Science Foundation (NSF) to design the first near-infrared tip-tilt sensor used to correct for the turbulence in Earth’s atmosphere. The improvements will increase the sensitivity and resolution of the Keck I telescope, which already allows astronomers to resolve in the near-infrared as much detail or more as the Hubble Space Telescope resolves in visible light.

The grant from NSF’s Advanced Technologies and Instrumentation (ATI) program provides the Observatory with the funding to design, construct and implement a near-infrared tip-tilt sensor with the Keck I Laser Guide Star (LGS) Adaptive Optics (AO) system and OSIRIS, a near-infrared integral field spectrograph and imager. An adaptive optics system removes the blurring effect of the Earth’s atmosphere, taking the twinkle out of stars. The new instrumentation will be developed in collaboration with Caltech Optical Observatories, which will be building the camera to be used in the sensor.

“Every innovative, significant adaptive optics improvement has triggered new discoveries, from the structure of the rings of Uranus, to direct imaging of extrasolar planets, to the size and nature of the environment around the Galaxy’s central black hole, to the morphology of high-redshift galaxies,” said Keck Observatory Director Taft Armandroff. “The Observatory’s new near-infrared sensor is a major advancement in adaptive optics and will contribute significantly to future discoveries.”

The current Keck LGS AO facilities use a wavefront sensor looking at a laser-based artificial star to measure the turbulence in the atmosphere and a deformable mirror to correct for this turbulence about 1000 times every second. The artificial star has no information about the image motion introduced by the atmosphere so currently a visible tip-tilt sensor is used to control a fast tip-tilt mirror in the AO system. The resulting images are sharp, allowing astronomers to observe minute details of cosmic objects, such as storms on Uranus or the shape of extremely distant galaxies.

The new infrared tip-tilt sensor will improve the AO performance by doing the tip-tilt sensing at near-infrared wavelengths where the stars images are smaller due to the corrections provided by the AO system, and where the stars are brighter. This will increase the amount of sky and number of cosmic objects astronomers can study with the Keck I LGS AO system. It will also provide even more resolution for astronomers to better study the birth of supermassive stars, the internal properties of early, star-forming galaxies and the existence of galaxies that have no stars and emit no light called dark matter galaxies.

In 1999, the Observatory implemented the first AO system on an 8-10 meter class telescope, the Keck II telescope, and then followed with a similar facility on Keck I in 2001. The Keck II facility was upgraded to a LGS AO facility in 2002 and a faster control system was incorporated in 2007.

The near infrared tip-tilt sensor upgrade is intended to maintain the Observatory’s global leadership in AO, and astronomy. With the funding, the team will continue to improve the Observatory’s AO system benefitting a significant number of astronomers, said Thomas Stalcup, the project manager for this NSF award.

Through NASA and the NSF/NOAO Telescope System Instrumentation Program, the entire U.S. community has access to the Observatory’s AO-corrected 10-meter telescopes. The Observatory provides a third of the overall U.S. community’s observing time on large telescopes, as well as to University of California, Caltech and University of Hawai’i astronomers.

The technology of adaptive optics “is amazing and the scientific applications fascinating. I study topics like galaxy formation, black holes, and gravitational lensing, all of which require the study of extremely faint and small targets,” said Tommaso Treu, an astronomer at the University of California, Santa Barbara and the principal scientist for the Observatory’s tip-tilt sensor. “For this reason, I am very interested in upgrades that can push the envelope of what is feasible with AO. The new tip-tilt sensor will be a major advance for my area of science, as well as many others.”

Peter Wizinowich, the principal investigator for this NSF award and the Observatory’s AO lead, added that the new sensor will not only directly produce significant science returns on an existing LGS AO facility. It will also provide an on-sky science demonstration of this key technology, identified as a top priority of the 2008 U.S. AO Roadmap for next generation AO systems on existing and extremely large telescopes.

Along with the tip-tilt sensor, Wizinowich and the AO team will improve the Keck II telescope’s LGS AO facility through a $1.3 million grant from NSF’s Major Research Instrumentation Program awarded in 2009. According Jason Chin, the award’s project manager, the funding will allow Keck AO scientists to design a laser launch telescope that will be positioned behind the telescope’s secondary mirror.

The laser is currently launched from the side of the Keck II telescope. The “center-launch” of the laser will provide even sharper science images with the existing Keck II LGS AO system, resulting in more precise brightness and position measurements of cosmic objects.

Both the new center-launch of the laser and the infrared tip-tilt sensor are steps towards the development of the Observatory’s Next Generation Adaptive Optics, or NGAO, system. NGAO is an innovative AO facility that will monitor and correct for atmospheric turbulence with multiple laser guide stars, advanced wavefront monitoring and extremely sensitive instrumentation. As the upgrades in Keck’s AO system evolve into NGAO, the Observatory’s telescopes will provide near infrared resolution equal to or better than that of the James Webb Space Telescope, currently the most sophisticated space-based observatory under construction.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org .

Reverse cosmic lens advances quasar studies

July 15, 2010

Kamuela, HI—Astronomers using Keck Observatory have identified the first known quasar acting as a gravitational lens that magnifies an even more distant galaxy. The discovery may provide astronomers with a new technique to study quasars.

Quasars are extraordinarily luminous and energetic objects that can be a thousand times brighter than ordinary galaxies, such as the Milky Way. They are thought to be powered by supermassive black holes that lie at the core of distant galaxies. Because quasars are so luminous and emit nearly all their light from the very innermost regions of their host galaxy, astronomers gather little information on the host galaxy itself.

“It is a bit like staring into bright car headlights and trying to discern the color of their rims,” said astronomer Frederic Courbin of the Ecole Polytechnique Federale de Lausanne, or EPFL, in Switzerland.

The new “reverse” quasar-galaxy gravitational lens, described by Courbin and his colleagues in the July 16 Astronomy & Astrophysics, provides a way to tell something about the host galaxy, such as its mass. This is important to studying how the galaxy itself relates to the central supermassive black hole.

According to Einstein’s theory of general relativity, a gravitational lens occurs when a large mass—a quasar, large galaxy or cluster of galaxies—is placed along the line of sight to a distant galaxy. As light from the distant galaxy travels toward Earth and interacts with the large mass, the distant object’s light rays are bent and re-directed. On Earth, an observer sees this interaction as two or more close images of the magnified background galaxy.

Astronomers discovered the first quasar gravitationally lensed by a foreground galaxy in 1979. Since then, they have found many more examples of quasar-galaxy gravitational lenses, allowing researchers to calculate the masses of the foreground galaxies.

There has not been an example of the reverse process—a background galaxy being lensed by the massive host galaxy of a foreground quasar—until now.

“We were delighted to see that this idea actually works,” said Georges Meylan, the leader of the EPFL team. “This discovery demonstrates the continued utility of gravitational lensing as an astrophysical tool.”

To find potentially lensing quasars, astronomers from EPFL and the California Institute of Technology, or Caltech, searched a large database of quasar spectra obtained by the Sloan Digital Sky Survey. The team selected candidates that showed evidence of reverse quasar-galaxy gravitational lensing.

Using the Keck II 10-meter telescope, the Near-Infrared Camera-2 (NIRC-2), and laser guide star adaptive optics to correct for the turbulence in the atmosphere, the astronomers imaged the candidate quasars. Pictures of one candidate revealed the signature multiple images of a lensed background galaxy.

With the Keck I 10-meter telescope and its Low Resolution Imaging Spectrograph, or LRIS, the team determined that the quasar is 1.6 billion light years from Earth and lenses a galaxy roughly 7.5 billion light years away. The astronomers also estimate that the inner kiloparsec, or 3200 light years, of the quasar’s host galaxy contains roughly 20 billion times the mass of the Sun.

“Quasars are valuable probes of galaxy formation and evolution,” said S. George Djorgovski, the leader of the Caltech team. “Discoveries of more of these systems will help us better understand the relationship between quasars and the galaxies which contain them, and their co-evolution.”

The Sloan Digital Sky Survey (SDSS) is one of the most ambitious and influential surveys in the history of astronomy. SDSS-III, a program of four new surveys using SDSS facilities, began observations in July 2008, and will continue through 2014. The SDSS used a dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico, equipped with two powerful special-purpose instruments.

Zooming in on Infant Planetary Systems

June 15, 2010

MAUNA KEA, HI—Using both 10-meter Keck telescopes together, astronomers at the W. M. Keck Observatory have been able to peer deeper into proto-planetary disks, swirling clouds of gas and dust that feed the growing stars in their centers and eventually coalesce into new planetary systems.

The team studied 15 young Milky Way stars varying in mass between one half and ten times that of the Sun and used the Keck Interferometer to obtain extremely fine observations to pinpoint the location of the processes that occur right at the boundary between the stars and their surrounding disks, which sit 500 light years from Earth.

The Keck Interferometer combines both 10-meter Keck telescopes to act as an 85-meter telescope, and is a project funded by NASA, in a partnership between the Jet Propulsion Laboratory, the NASA Exoplanet Science Institute and the Keck Observatory. Four years ago, with a grant from the National Science Foundation, a quest began to expand the astrometric capability of the Keck Interferometer with a specifically engineered instrument named ASTRA, or ASTrometric and phase-Referenced Astronomy.

ASTRA aims to provide extremely precise measurements of the positions and movements of stars, gas and dust. “With it in its current state, we are going for young stars and their dust disks,” said Keck Observatory scientist Julien Woillez, co-investigator of the new research and lead of the ASTRA instrument. “As we improve ASTRA, we will soon have the capability to study the motion of planets around older stars, and even the motion of stars around the black hole at the center of our Galaxy.”

The resolution achieved in this study, which will be published in the July 20 Astrophysical Journal, allowed the team to observe proto-planetary disk material within 0.1 astronomical units, or nine million miles, of the target star. One astronomical unit is roughly 93 million miles, or the distance between the Sun and Earth. The precision measurements would be similar to standing on a rooftop in San Francisco and trying to observe a Nene goose nibbling on a grain of rice in Hawai’i.

Stars’ proto-planetary disks form in stellar nurseries when clouds of gas molecules and dust particles begin to collapse under the influence of gravity. Initially rotating slowly, the cloud’s growing mass and gravity cause it to become denser and more compact. Preserving rotational momentum, the cloud begins to spin faster and shrinks, similar to a figure skater spinning faster as she pulls in her arms. The centrifugal force flattens the cloud into a spinning disk of swirling gas and dust — eventually giving rise to planets orbiting their star in roughly the same plane.

Measuring the light emanating from the proto-planetary disks at different wavelengths with the Keck Interferometer and manipulating it further with ASTRA, the astronomers were able to distinguish between the distributions of gas, mostly made up of hydrogen, and dust, thereby resolving the disk’s features.

Astronomers know that stars acquire mass by incorporating some of the hydrogen gas in the disk that surrounds them, in a process called accretion. The team wants to better understand how material accretes onto the star, a process that has never been measured directly, said Joshua Eisner of the University of Arizona and lead author of the paper.

In proto-planetary disks, accretion can happen in one of two ways.

In one scenario, gas is swallowed as it washes up right to the fiery surface of the star. In the second, much more violent scenario, the magnetic fields sweeping from the star push back the approaching gas and cause it to bunch up, creating a gap between the star and its surrounding disk. Rather than lapping at the star’s surface, the hydrogen molecules travel along the magnetic field lines as if on a highway, becoming super-heated and ionized in this process.

“Once trapped in the star’s magnetic field, the gas is being funneled along the field lines arching out high above and below the disk’s plane,” Eisner explained. “The material then crashes into the star’s polar regions at high velocities.”

In this inferno, which releases the energy of millions of Hiroshima-sized atomic bombs every second, some of the arching gas flow is ejected from the disk and spews out far into space as interstellar wind.

“We could successfully discern that in most cases, the gas converts some of its kinetic energy into light very close to the stars,” he said, a tell-tale sign of the more violent accretion scenario.

“In other cases, we saw evidence of winds launched into space together with material accreting on the star,” Eisner added. “We even found an example—around a very high-mass star—in which the disk may reach all the way to the stellar surface.”

Because the disks are young, only a few million years, they will be around for a few more millions of years. “By that time, the first planets, gas giants similar to Jupiter and Saturn, may form, using up a lot of the disk material.”

More solid, rocky planets like the Earth, Venus or Mars, won’t be around until much later.

The building blocks for those more terrestrial planets could be forming now, he added, which is why this research is important for our understanding of how planetary systems form, including those with potentially habitable planets like Earth.

“We are going to see if we can make similar measurements of organic molecules and water in proto-planetary disks,” Eisner said. “Those would be the ones potentially giving rise to planets with the conditions to harbor life.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California, and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org .

Keck Observatory Project Scientist wins 2010 Kavli Prize

June 3, 2010

KAMUELA, HI—Jerry Nelson, an astronomer at the University of California, Santa Cruz, and designer of the revolutionary segmented-mirror Keck telescopes will share the $1 million Kavli Prize in Astrophysics with two other researchers for their innovations in the field of telescope design.

The achievements of Nelson and his co-recipients—Roger Angel of the University of Arizona, Tucson, and Ray Wilson, formerly of Imperial College London and the European Southern Observatory—have made possible the building of telescopes that can peer deeper into space and further back in cosmic time.

“Keck Observatory is the incarnation and validation of Jerry Nelson’s concept of the segmented mirror. He was the Project Scientist for the development of Keck Observatory, and his work has established today’s incredible era of astronomy discovery. This is a well-deserved award,” said W. M. Keck Observatory Director Taft Armandroff.

Nelson, Angel and Wilson are among eight scientists whose discoveries in the fields of astrophysics, nanoscience, and neuroscience have been recognized with the award of the 2010 Kavli Prizes, announced today by the Norwegian Academy of Science and Letters. The laureates will each receive a scroll, a gold medal, and a share of the $1 million prize for each of the three fields.

Nelson is internationally renowned as a developer of innovative designs for advanced telescopes. He conceived of the revolutionary segmented design of the W. M. Keck Observatory’s 10-meter primary mirrors. As founding director of the Center for Adaptive Optics, a National Science Foundation science and technology center headquartered at UC Santa Cruz, Nelson helped pioneer the use of adaptive optics for astronomy, enabling scientists to get sharp images from ground-based telescopes. Adaptive optics corrects the blurring of telescope images caused by turbulence in the atmosphere. Keck Observatory was the first large ground-based telescope to employ adaptive optics and later a laser guide star adaptive optics system.

Nelson earned a B.S. in physics from the California Institute of Technology and a Ph.D. in physics from UC Berkeley. He is a member of the National Academy of Sciences and has received numerous awards and honors for his work, including the André Lallemand Prize of the French Academy of Sciences and the American Astronomical Society’s Dannie Heineman Prize for Astrophysics.

Angel and Wilson are also pioneers in telescope design. Angel created mirrors made of cheap glass and molded them to incorporate a honeycomb pattern of holes to reduce their weight and increase their rigidity, allowing the building of larger telescopes. Wilson developed the concept of active control of optics, particularly for large monolithic mirrors; using computer-controlled actuators to make small, constant changes to telescope mirror shapes during use corrects for distortions caused by gravity, wind, and temperature.

Nelson is now project scientist for the Thirty Meter Telescope , or TMT, which is currently in the design phase. The TMT will have a 30-meter primary mirror, with 492 segments, and will use similar technology developed for the precision control, segmented mirror design, and adaptive optics of the Keck Observatory.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California, and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org .

The biennial Kavli Prizes were first awarded in 2008. They were set up to recognize outstanding scientific research, honor highly creative scientists, promote public understanding of scientists and their work, and encourage international scientific cooperation. The prizes are a partnership of the Norwegian Academy of Science and Letters, the Kavli Foundation, and the Norwegian Ministry of Education and Research. More information is available online at http://www.kavliprize.no.

Steidel receives Gruber Cosmology Prize for observations of earliest galaxies

June 2, 2010

NEW YORK, NY – Charles Steidel, the Lee A. DuBridge Professor of Astronomy at the California Institute of Technology, is the recipient of the 2010 Cosmology Prize of The Peter and Patricia Gruber Foundation. The award recognizes Steidel’s revolutionary studies using the W. M. Keck Observatory of the most distant galaxies in the Universe.

“Professor Steidel pioneered the techniques needed to find young galaxies and led the efforts that have opened a direct observational window to a time when the Universe was only about one tenth of its current age,” the official citation said. Steidel will receive the $500,000 award, as well as a gold medal, in October at the University of Chicago in Chicago, Illinois, where he will also deliver a lecture.

“My main scientific interest is, and has been, how did the first galaxies form? When did they form and has the way that galaxies form changed over time?” Steidel said.

In order to answer those questions, he and his colleagues needed to observe galaxies at different stages of the Universe’s history. The astronomers were especially interested in so-called “primordial galaxies,” which date from a period of more than 12 billion years ago, when the Universe was less than two billion years old.

Astronomers had already observed a handful of objects at such a distance, but most were extreme, such as quasars and not normal, star-forming galaxies. Steidel realized, however, that stars, and therefore galaxies, are rich in hydrogen. Hydrogen absorbs radiation with wavelengths shorter than 91.2 nanometers—what astronomers call the Lyman limit. As a result, galaxies are mostly invisible below the Lyman limit, in the far ultraviolet region of the electromagnetic spectrum, but visible above it.

Although light with a wavelength of 91.2 nanometers is not accessible on Earth due to the interference of the atmosphere, Steidel and his colleagues knew that the expansion of the Universe would stretch the length of the waves until they were visible. And, they knew a wave of light with a length of 91.2 nanometers that traveled 12 billion lightyears would have stretched to wavelengths observable with ground-based telescopes. If they could observe these distant objects and detect a sharp cutoff, or break, at that wavelength, they would know the objects were galaxies.

After outlining their approach in papers now considered classics, Steidel and his colleagues discovered their first batch of distant galaxies, called Lyman Break Galaxies, in October 1995, using the Keck I telescope and its Low Resolution Imaging Spectrograph.

“My entire scientific focus came to be during my first nights on the Keck telescope in 1995. Ever since then, I think of Keck as an extension of where I work, almost like an extended family,” Steidel said. His team’s observations using his new technique were the first to show that galaxies were common, even at such an early point in the Universe’s evolution.

“Using Keck, Chuck Steidel has revolutionized our understanding of how galaxies in the early Universe form and change over cosmological time. His work is very deserving of this prestigious award,” said Taft Armandroff, the director of the W. M. Keck Observatory.

Steidel’s award is the second Gruber Prize for Cosmology given to an astronomer whose scientific discoveries were made using data taken with the Keck telescopes. In 2007, two teams led by Saul Perlmutter and Brian Schmidt, respectively, received the award to recognize their observations revealing that the expansion of the Universe is accelerating. Their discovery led to the idea of an expansion force, called dark energy.

In the past five years, Steidel has extended his study of galaxy formation by moving somewhat forward in time, to the period about 10 to 12 billion years ago—a peak era for star formation, supernova explosions, and the accumulation of gas by supermassive black holes. This year he is publishing his first paper about a new technique that uses multiple “skewers” of one-dimensional views through the Universe to create a composite 3-D view of these highly active galaxies spewing gas into intergalactic space. Using this method, Steidel and his team have discovered that a galaxy can influence a region in space one hundred times the diameter of the galaxy itself.

“How do you efficiently find lots and lots of galaxies wherever you want at a particular point in the sky at a particular distance in order to isolate a particular period in the history of the Universe?” Steidel said. Over the past twenty years, he has provided many of the answers, and his work has helped expand cosmology from the study of the evolution of the Universe as a whole to the study of cosmic evolution of its parts—galaxies.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California, and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org .

The Peter and Patricia Gruber Foundation honors and encourages educational excellence, social justice and scientific achievements that better the human condition. For more information about Foundation guidelines and priorities, please visit http://www.gruberprizes.org and www.facebook.com/gruberprizes.

Possible new type of supernovae puts calcium in your bones

May 19, 2010

KAMUELA, HI — New data from several telescopes, including the W. M. Keck Observatory, suggest astronomers may have identified a new type of supernovae. The stellar death is thought to have originated in a star that was a low-mass white dwarf accumulating helium from a companion star. When the white dwarf exploded, about half of the mass ejected from the supernova was in the form of calcium. The finding suggests that a couple of supernovae like this exploding every 100 years would produce the high abundance of calcium observed in galaxies like the Milky Way, and the calcium present in life on Earth.

The supernova, SN 2005E, was discovered five years ago by the University of California, Berkeley’s Katzman Automatic Imaging Telescope (KAIT), and is one of only eight known “calcium-rich supernovae” that appear to be distinct from the two main classes of supernovae: the Type Ia supernovae, thought to be old, white dwarf stars that accrete matter from a companion until they undergo a thermonuclear explosion that blows them apart entirely; and Type Ib/c or Type II supernovae, thought to be hot, massive and short-lived stars that explode and leave behind black holes or neutron stars.

In the past decade, robotic telescopes have turned astronomers’ attention to scads of strange exploding stars, one-offs that may or may not point to new and unusual physics. “With the sheer numbers of supernovae we’re detecting, we’re discovering weird ones that may represent different physical mechanisms compared with the two well-known types, or may just be variations on the standard themes,” said Alex Filippenko, KAIT director and UC Berkeley professor of astronomy. “But SN 2005E was a different kind of ‘bang.’ It and the other calcium-rich supernovae may be a true suborder, not just one of a kind.”

Filippenko is coauthor of a paper appearing in the May 20 issue of the journal Nature describing SN 2005E and presenting evidence that the original star was a low-mass white dwarf stealing helium from a binary companion until the temperature and pressure ignited a thermonuclear explosion – a massive fusion bomb – that blew off at least the outer layers of the star and perhaps blew the entire star to smithereens. The team of astronomers was led by Hagai Perets, now at the Harvard-Smithsonian Center for Astrophysics, and Avishay Gal-Yam of the Weizmann Institute of Science in Rehovot, Israel.

In November 2009, Filippenko and former UC Berkeley post-doctoral fellow Dovi Poznanski, currently at Lawrence Berkeley National Laboratory and also coauthor on the Nature paper, reported another supernova, SN 2002bj, that they believe explodes by a similar mechanism: ignition of a helium layer on a white dwarf.

“SN 2002bj is arguably similar to SN 2005E, but has some clear observational differences as well,” Filippenko said. “It was likely a white dwarf accreting helium from a companion star, though the details of the explosion seem to have been different because the spectra and light curves differ.” Astronomers have so far found only one example of this supernova.

Filippenko and UC Berkeley research astronomer Weidong Li first reported an unusual calcium-rich supernova in 2003, and since then, KAIT has discovered several more, including SN 2005E on Jan. 13, 2005. Because these supernovae, like Type Ib, show evidence for helium in their spectra shortly after they explode, and because in the later stages they show strong calcium emission lines, the UC Berkeley astronomers were the first to refer to them as “calcium-rich Type Ib supernovae.”

It was SN 2005E, which went off about 110 million years ago in the spiral galaxy NGC 1032 in the constellation Cetus, that initially drew the attention of Perets, Gal-Yam and their colleagues. Using data provided by Filippenko and Li, and taken by the W. M. Keck Observatory in Hawaii, the Palomar Observatory in California and the Liverpool Observatory in the United Kingdom, they created a detailed picture of the explosion. The small amount of mass ejected in the explosion, estimated at 30 percent the mass of the Sun, and the fact that the galaxy in which the explosion occurred was old with few hot, giant stars, led them to the conclusion that a low-mass white dwarf was involved.

The newly discovered supernova threw off unusually high levels of the elements calcium and radioactive titanium, which are the products of a nuclear reaction involving helium rather than carbon and oxygen that are involved in Type Ia supernovae.

“We know that SN 2005E came from the explosion of an old, low-mass star because of its specific location in the outskirts of a galaxy devoid of recent star formation,” Filippenko said. “And the presence of so much calcium in the ejected gases tells us that helium must have exploded in a nuclear runaway.”

The paper’s authors note that, if these eight calcium-rich supernovae are the first examples of a common, new type of supernovae, they could explain two puzzling observations: the abundance of calcium in galaxies and in life on Earth, and the concentration of positrons – the anti-matter counterpart of the electron – in the center of galaxies. The latter could be the result of the decay of radioactive titanium-44, produced abundantly in this type of supernova, to scandium-44 and a positron, prior to scandium’s decay to calcium-44. The most popular explanation for this positron presence is the decay of putative dark matter at the core of galaxies.

“Dark matter may or may not exist,” says Gal-Yam, “but these positrons are perhaps just as easily accounted for by the third type of supernova.”

Filippenko and Li hope that KAIT and other robotic telescopes scanning distant galaxies every night in search of new supernovae will turn up more examples of calcium-rich or even stranger supernovae, which can then be observed with larger telescopes such as Keck.

“The research field of supernovae is exploding right now, if you’ll pardon the pun,” Filippenko said. “Many supernovae with peculiar new properties have been found, pointing to a greater richness in the physical mechanisms by which nature chooses to explode stars.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California, and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org .

Keck Observatory showcases local artist’s work

May 6, 2010

KAMUELA, HI—Laurie Goldstein, a resident of North Kohala, will present a mixed media art show, entitled “Universe in Color” at the W. M. Keck Observatory headquarters, located at 65-1120 Mamalahoa Highway, in Waimea. The exhibit runs from May 20 to September 22.

Public viewing of Goldstein’s art will be available during Keck Observatory’s monthly astronomy lectures. “It is a pleasure to be able to showcase Laurie’s work for friends of Keck astronomy. Our conference room is traditionally at maximum capacity for our lectures and serves as a unique, alternative gallery for our community,” said Observatory Director Dr. Taft Armandroff. The next astronomy lecture will be held Thursday, June 10 at 7:00 p.m.

Goldstein created her first work of art at age five. With a cardboard tracing of her foot, some ribbon and blue and gold paint, she crafted a pair of Grecian sandals. “I have no idea where I’d seen something like that or how I figured out how to make them,” she said, “but the joy of making art has been with me ever since.”

After her school days, Goldstein began her formal art career as a printmaker, focusing primarily on monotype prints. She then gradually began adding thin papers and fabrics to her pieces, which have evolved from prints to print collages and finally to collage on canvas.

“In my current work, the background is usually an acrylic painted canvas. I mix paints to get the colors I want and then paint papers for tearing or cutting. This way I can get exactly the color, texture and shape I want for the pieces,” Goldstein said.

Her latest work features canvas with papers, fabrics and ephemera glued to the surface. Goldstein explained that she sometimes paints over the collage material to give the surface texture, creating shapes that help dictate the outcome of the piece. In other works, she has used the glued materials as the final layer, which leaves the textures and colors of the collaged pieces completely visible.

“It’s always fun to see how the final piece differs from what I may have had in my mind when starting it,” she said.

Goldstein’s works are featured in several museums and corporate and private collections including: the National Art Library of the Victoria and Albert Museum, in London, England, the Library of the Museum of Modern Art, in New York City and the Library of the National Museum of American Art, in Washington, D.C. as well as Bristol-Myers Squibb headquarters in Princeton, New Jersey and Johnson & Johnson headquarters, in New Brunswick, New Jersey.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California and NASA. The Observatory’s headquarters in Waimea has a visitors’ center open to the public Tuesday through Friday 10 a.m. to 2 p.m. For more information, please call 808.881.3827 or visit http://www.keckobservatory.org .

Astronomers See Historical Supernova From New Angle

March 31, 2010

MAUNA KEA, HI— By observing visible “light echoes,” astronomers have assembled one of the first 3-D perspectives of a cosmic object. The new view of the supernova remnant Cassiopeia A confirms that it formed during a lopsided explosion.

“Light echoes allow us to conduct forensic studies of stars that exploded long ago,
before modern astronomical instruments became available,” said astronomer Alex Filippenko of the University of California, Berkeley. “It’s kind of like getting photographs of a crime that was committed years ago, before cameras existed.”

Filippenko and his collaborators made the light-echo measurements of Cassiopeia A, which is located about 16,000 light years from Earth, based on the familiar concept of a sound echo. If a person yells “Echo!” in a cave, the sound waves bounce off the walls and reflect back to his ears, or the ears of other people, as echoes. A similar phenomenon occurs with light.

The supernova’s light, for example, reflects off interstellar clouds of dust, creating light echoes that come toward Earth from different directions, depending on where the clouds are located.

“Just like mirrors in a changing room show you a clothing outfit from all sides, interstellar dust clouds act like mirrors to show us different sides of the supernova,” said Armin Rest of Harvard University, the lead investigator of the project.

Most of Cassiopeia A’s light washed over the Earth about 330 years ago and is long gone. But light that took a longer path, reflecting off clouds of interstellar dust, is just now reaching the planet. This faint, reflected light is what the astronomers detected as light echoes using the Mayall 4-meter telescope at Kitt Peak National Observatory in Arizona.

They then used the 10-meter Keck I telescope on Mauna Kea to obtain high-quality spectra of the light echoes, which are several million times fainter than the faintest stars visible to the unaided eye in dark skies. Keck’s Low Resolution Imaging Spectrometer spread out the light from each echo into its component colors, or spectrum, and from this, the astronomers were able to measure the expansion speeds of the ejected gases.

“One of the big uncertainties in our understanding of how massive stars explode is whether the explosions are spherically symmetric, the same in all directions,” said Filippenko, who conducted the supernova echo project at the Keck Observatory. “Up until now, we have had some indirect evidence for asymmetries, but our new Keck observations of light echoes directly reveal them.”

Each echo comes from a spot with a different view of the explosion. The Keck spectra ultimately revealed that the gas was streaming away from the remnant in one direction at a speed of almost nine million miles per hour (or 2,500 miles per second) faster than gas moving in the other two observed directions.

Previous studies support the team’s findings. The neutron star, created when the core of the original star in Cassiopeia A collapsed, is zooming through space at nearly 800,000 miles per hour, in the opposite direction of the unique light echo. The explosion may have kicked gas one way and the neutron star out the other side, a consequence of Newton’s third law of motion, which states that every action has an equal and opposite reaction.

“Now we can connect the dots from the explosion itself, to the supernova’s light, to the supernova remnant,” said Ryan Foley of the Harvard-Smithsonian Center for Astrophysics and co-author of the new paper. Filippenko noted that theoretical astrophysicists will now definitely need to include asymmetries in their physical models of how massive, dying stars explode.

The results have been submitted for publication in the Astrophysical Journal.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California, and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org

Keck telescope confirms smallest known star duo

March 8, 2010

Astronomers using the W. M. Keck Observatory have identified the smallest known binary system to date. The system, called HM Cancri, consists of two dead stars that revolve around each other in 5.4 minutes, by far the shortest known orbital period of any pair of stars.

The team, led by Gijs Roelofs of the Harvard-Smithsonian Center of Astrophysics, used the 10-meter Keck I telescope with its Low Resolution Imaging Spectrograph to study the velocity changes in the spectral lines in the light of HM Cancri. They observed that as the stars orbited each other, the system’s spectral lines shifted periodically from blue to red and back following the Doppler Effect. With the velocity information, the astronomers were able to confirm the binary’s 5.4-minute period. The results appear in the March 10 Astrophysical Journal Letters.

“When the first data from the Keck telescope arrived, and our quick analysis showed the periodic shift of the spectral lines, we knew that we had succeeded. More than ten years after its discovery, we finally had deciphered the nature of HM Cancri,” said Arne Rau of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, who led the observations at Keck.

Astronomers proposed several years ago that HM Cancri was an interacting binary consisting of two dead stars and that the 5.4 minute period observed was indeed the orbital period. “It is very gratifying to see this model confirmed by our observations, especially since earlier attempts had been thwarted by bad weather,” said Daniel Steeghs of the University of Warwick, UK. The team had been trying to make precise velocity measurements to confirm the period since 2005.

HM Cancri was discovered in 1999 as a weak X-ray source in data from the German ROSAT satellite. It consists of two white dwarfs, burnt-out cinders of stars that were once similar to the Sun and contain a highly condensed form of helium, carbon and oxygen. In 2001, the X-ray, and also optical, data suggested that the two stars orbited each other in 5.4 minutes.

But this information suggested that the binary system was roughly eight times the diameter of the Earth—equivalent to a quarter of the distance between the Earth and the Moon—or smaller. Astronomers were reluctant to accept this physical description of HM Cancri without additional evidence. But even at a distance of 16,000 light years from Earth, the binary system shines only one millionth as bright as the faintest stars visible to the naked eye.

To determine with certainty the period of such a system, astronomers needed to use world’s largest telescopes to collect the additional evidence. “This type of observation is really at the limit of what is currently possible. Not only does one need the biggest telescopes in the world, but they also have to be equipped with the best instruments available,” said team member Paul Groot of the Radboud University Nijmegen in the Netherlands.

As a result of the successful observations with Keck, astronomers now have a new cosmic laboratory to study the evolution of stars as well as general relativity. “We know the system must have come from two normal stars that somehow spiraled together in two earlier episodes of mass transfer, but the physics of this process is very poorly understood,” said Gijs Nelemans of the Radboud University who was also part of the team.

He added that the system must be one of the most copious emitters of gravitational waves. “We hope to detect these distortions of space-time directly with the future LISA satellite. HM Cancri will now be a cornerstone system for the mission,” he said.

New tidal streams found in Andromeda reveal history of galactic mergers

January 7, 2010

WASHINGTON D.C.—The Andromeda galaxy has two previously unknown tidal streams, according to data recently taken at the W. M. Keck Observatory and Subaru Telescope. The coherent flows of stars are remnants of dwarf galaxies that Andromeda has been consuming over the last one to two billion years.

The Andromeda galaxy is a unique test bed for studying the formation and evolution of a large galaxy, said Puragra Guhathakurta, of the University of California, Santa Cruz. He leads the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH), an international collaboration conducting a large survey of red giant stars in Andromeda.

Tidal streams are important because they represent a conceptual “link” or “bridge” between the victims and survivors of galactic cannibalism, an intermediate stage between the population of intact dwarf galaxies and the merged or dissolved dwarf galaxies whose stars are now well mixed in the parent galaxy’s halo, he explained.

Guhathakurta announced the discovery of the two new streams at the 215th meeting of the American Astronomical Society held Jan. 4-7, 2010 in Washington D.C.

In the currently favored Lambda Cold Dark Matter paradigm of structure formation in the Universe, the outer halos of large galaxies like the Milky Way galaxy and the neighboring Andromeda galaxy are built up through the merger and dissolution of smaller “dwarf” satellite galaxies. “This process of galactic cannibalism is an integral part of the growth of galaxies,” he said.

Discovery of the two tidal streams supports this idea of galactic cannibalism. Japanese astronomers first observed them when using the Subaru 8-meter telescope and Suprime-Cam camera to map the density of red giant stars in large portions of the Andromeda galaxy, including the previously uncharted north side. This revealed the streams on the northwest (streams E and F) at projected distances of 200,000 and 300,000 light years from Andromeda’s center. The study also confirmed a few previously known streams, including the little-studied diffuse stream to the southwest (stream SW), which lies at a projected distance of 200,000-300,000 light years from Andromeda’s center.

The SPLASH researchers followed up with a spectroscopic survey of several hundred red giant stars in Streams E, F, and SW, using the Keck II 10-meter telescope and DEIMOS spectrograph at the W. M. Keck Observatory in Hawai’i. The spectrograph spreads out the light from each star in to a spectrum, which allows astronomers to measure the velocity of the star and distinguish Andromeda red giant stars from foreground stars in the Milky Way. The spectral data confirmed the presence of the groups of Andromeda red giant stars moving with a common velocity.

One of the next steps using the Keck data will be to measure the chemical properties of red giant stars in these newly discovered tidal streams in Andromeda, Guhathakurta said.
Comparing the chemical properties of tidal streams, intact dwarf satellites and the smooth halo will provide details about galaxy cannibalism.

Dwarf galaxies are less effective at recycling chemical elements than massive galaxies. This is partly because the weaker gravity of a dwarf galaxy makes it harder for it to retain the chemically enriched gas that is blown out of massive stars during supernova explosions. As a result, stars in dwarf galaxies are more anemic (have a smaller fraction of complex elements) than those in the interior of massive galaxies. Moreover, the action of merging with a larger galaxy causes a dwarf galaxy to lose its gas, breaking the chemical cycle altogether.

“The cannibalized victims have had less time to recycle their chemicals than dwarf galaxy survivors, and this should be reflected as a difference between their chemical properties,” Guhathakurta said. “Tidal streams should be somewhere between the victims and the survivors in terms of their chemical properties.”

Subaru is an 8.2-meter optical-infrared telescope at the summit of Mauna Kea, Hawaii, operated by the National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences.

Caption: Distribution of line-of-sight velocities of stars in the Stream SW field. The filled portion of the histogram corresponds to Andromeda red giant stars while the open portion corresponds to foreground Milky Way stars. The concentration of red giant stars (at a velocity of -370 kilometers per second) is characteristic of tidal streams. The mean velocity of the Andromeda galaxy is -300 kilometers per second, so this shows that Stream SW is moving towards us at 70 kilometers per second relative to the parent galaxy. In addition to the red giants in Stream SW, there is a population of red giants with a broad distribution of velocities that represents the smooth halo of Andromeda built from the dissolved dwarf galaxy victims of the cannibalism process. Credit: Raja Guhathakurta, UCSC.

Second smallest exoplanet found to date discovered at Keck

January 7, 2010

WASHINGTON D.C.— Planet hunters using Keck Observatory have detected an extrasolar planet that is only four times the mass of Earth. The planet is the second smallest exoplanet ever discovered and adds to astronomers’ growing cadre of low mass planets called super-Earths.

“This is quite a remarkable discovery,” said astronomer Andrew Howard of the University of California at Berkeley, or UCB. “It shows that we can push down and find smaller and smaller planets.” He announced the discovery at the 215th American Astronomical Society meeting held Jan. 4-7, 2010 in Washington D.C.

Dubbed HD156668b, the planet orbits its parent star in just over four days and is located roughly 80 light years from Earth in the direction of the constellation Hercules. Howard, along with his colleagues from the California Planet Search team (CPS) Geoff Marcy of UCB, Debra Fischer of Yale University, John Johnson of the California of Institute of Technology and Jason Wright of Penn State University, discovered the new planet with the 10-meter Keck I telescope atop Mauna Kea in Hawai’i.

The researchers used the radial velocity or wobble method, which relies on Keck’s High Resolution Echelle Spectrograph, or HIRES instrument, to spread light collected from the telescope into its component wavelengths or colors. The result is called a spectrum. When the planet orbits around the back of the parent star, its gravity pulls slightly on the star causing the star’s spectrum to shift toward redder wavelengths. When the planet orbits in front of the star, it pulls the star in the other direction. The star’s spectrum shifts toward bluer wavelengths.

The color shifts give astronomers the mass of the planet and the characteristics of its orbit, such as the time it takes to orbit the star. Nearly 400 planets around other stars were discovered using this technique. But, the majority of these planets are Jupiter-sized or larger.

“It’s been astronomers long-standing goal to find low mass planets, but they are really hard to detect,” Howard said. He added that the new discovery has implications for not only exoplanet research but also for solving the puzzle of how planets and planetary systems form and evolve.

Astronomers have pieces of the formation and evolutionary puzzle from the discovery of hundreds of high-mass planets. But, “there are important pieces, we don’t have yet. We need to understand how low mass planets, like super-Earths, form and migrate,” Howard said.

The goal of the Eta-Earth Survey for Low Mass Planets, which was the brainchild of Marcy, was to find these super-Earths. So far the survey has discovered two near-Earth-mass planets with more are on the way, Howard said.

He and his colleagues were granted time at Keck Observatory through NASA and the University of California.

Waltzing black holes take center stage at astronomy meeting

January 4, 2010

WASHINGTON D.C.—Astronomers using the W. M. Keck Observatory have discovered 33 pairs of black holes in distant galaxies. The new results verify that these waltzing black holes are more common than previously observed.

Nearly every galaxy has a central, supermassive black hole, typically with a mass of a million to a billion times the mass of the Sun. Galaxies also commonly collide and merge to form new, more massive galaxies. Astronomers therefore expect that many “waltzing” supermassive black holes exist in the Universe.

The new results provide some confirmation of this expectation, said Julia Comerford of the University of California, Berkeley, during the 215th American Astronomical Society meeting in Washington, DC.

Comerford and her colleagues studied 33 dual black holes, which appear to waltz in a dance choreographed by Isaac Newton’s laws of physics. Many galaxies will eventually do such a dance, including the Milky Way and the Andromeda galaxies when they collide in about three billion years.

The light used to observe the waltzing pairs comes from the gas collapsing onto the black holes. The gas releases energy and powers each black hole as an active galactic nucleus (AGN), lighting it up like a Christmas tree, Comerford said.

Thirty-two of the black holes in the new study were identified in the DEEP2 Galaxy Redshift Survey and are located in galaxies at distances 4 to 7 billion light years from Earth. The researchers used the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the 10-meter Keck II Telescope on Mauna Kea, Hawai’i to measure the redshifted light from a black hole as it moved away from the telescope and blueshifted light as it moved toward the telescope.

Each black hole’s velocity was measured to be a few hundred kilometers per second or “800 times the cruising speed of a jet airliner,” Comerford said. She added that the distance between the two black holes is roughly 3,000 light years, or roughly one-eighth the distance from the Sun to the center of the Milky Way Galaxy. The Sun sits roughly 26,000 light years from the Galactic Center.

The researchers identified one galaxy, COSMOS J100043.15+020637.2, however, in an image taken by the Advanced Camera for Surveys on the Hubble Space Telescope. The galaxy is located four billion light years from Earth.

Comerford explained that the galaxy’s tidal tail of stars, gas and dust—an unmistakable sign that the galaxy had recently merged with another galaxy—as well its prominently featured two bright nuclei near its center, led the team to become “smitten” with the galaxy.

To determine whether the two bright nuclei might be the AGNs of two waltzing black holes, the researchers then observed the galaxy with the Keck II telescope and its DEIMOS spectrograph. The spectra confirmed that the two central nuclei in the galaxy were both AGNs and were most likely on a path toward merging, she explained. The measured distance between the two black holes is 8000 light years—roughly one-third the distance between the Sun and the Galactic Center.

Francesca Civano of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. also presented findings on the same COSMOS galaxy during the conference. Civano, however, argued that instead of observing a pair of waltzing a black holes, astronomers are seeing one of the black holes as it is recoiling and being kicked out of the galaxy.

Either scenario—waltzing or recoiling black holes—hint at the merger of supermassive objects, Comerford explained. The researchers, however, need additional observations to distinguish between a pre-merger waltz or a post-merger recoil. Both researchers plan to use the Keck telescopes to collect future data, the astronomers said.

Keck telescopes take deeper look at planetary nurseries

December 23, 2009

MAUNA KEA, HI—Astronomers using the W. M. Keck Observatory have peered far into a young planetary system, giving an unprecedented view of dust and gas that might eventually form worlds similar to Jupiter, Venus or even Earth.

“Because the gas, dust and debris that orbit young stars provide the raw materials for planets, probing the inner regions of those stars lets us learn about how Earth-like planets form,” said astronomer Sam Ragland of Keck Observatory. He and his collaborators recently measured the properties of a young planetary system at distances closer to the star than Venus is to the Sun.

The researchers used the Keck Interferometer, which combines the light-gathering power of both 10-meter Keck telescopes to act as an 85-meter telescope, much larger than any existing or planned telescope.

“Nothing else in the world provides us with the types of measurements the Keck Interferometer does,” said Wesley Traub of Caltech’s Jet Propulsion Laboratory. “In effect, it’s a zoom lens for the Keck telescopes.”

The “zoom lens” allowed the researchers to probe MWC 419, a blue, B-type star that has several times the mass of the Sun and lies about 2,100 light-years away in the constellation Cassiopeia. With an age less than ten million years, MWC 419 ranks as a stellar kindergartener.

With the interferometer and the increased ability to observe fine detail, the team measured temperatures in the planet-forming disk to within about 50 million miles of the star. “That’s about half of Earth’s distance from the Sun, and well within the orbit of Venus,” said team member William Danchi of NASA’s Goddard Space Flight Center in Greenbelt, Md.

For comparison, astronomers using a single telescope have directly observed HR 8799, Fomalhaut and GJ 758 and their orbiting planets, which are 40 to 100 times farther away from their stars.

The interferometry results were taken in near-infrared light (3.5 to 4.1 micrometers), which is a wavelength slightly longer than red light and is invisible to the human eye. The researchers used a newly implemented infrared camera, which is the only one of its kind on Earth, to make the first “L-band” interferometric observations of MWC 419.

“This unique infrared capability adds a new dimension to the Keck Interferometer in probing the density and temperature of planet-forming regions around young stars. This wavelength region is relatively unexplored,” Ragland said. “Basically, anything we see through this camera is brand new information.”

With the data, Ragland and his collaborators measured the temperature of dust at various regions throughout MWC 419’s inner disk. Temperature differences throughout the disk may indicate that the dust has different chemical compositions and physical properties that may affect how planets form. For example, in the Solar System, conditions were just right to allow rocky worlds to form closer to the Sun, while gas giants and icy moons assembled farther our in the system. The team reported their findings in the Sept. 20 issue of the Astrophysical Journal.

The observations are an “important first step” in a larger program to collect data on young stars that span the lower-mass T Tauri stars, which are the progenitors of Sun-like stars, to their more massive counterparts, like MWC 419, explained John Monnier, an interferometry scientist at the University of Michigan who was not involved with the study.

The astronomers want to study the range of developing stars because their mass, size and luminosity might affect the composition and physical characteristics of the surrounding disk. Ragland and his collaborators are continuing to collect data on young stars and will combine their infrared observations with new data from the Keck Interferometer’s “nulling” mode, a technique which will block out the light from the central star in a young planetary system.

The Keck Interferometer is funded by NASA and developed by the Keck Observatory, the Jet Propulsion Laboratory (California Institute of Technology) and the NASA Exoplanet Science Institute (California Institute of Technology). The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i and is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

First super-earths discovered around sun-like stars

December 14, 2009

MAUNA KEA, HI—Planet hunters using the W. M. Keck Observatory have identified at least six low-mass planets around two nearby, Sun-like stars. Two of the planets are five and 7.5 times the mass of Earth. These “super-Earths” are the first low mass planets found orbiting stars similar to the Sun.

The latest discoveries probe a new class of planets that are somewhat more massive than Earth but less massive than Uranus and Neptune, which suggests that low mass planets are quite common around nearby stars, said expert planet hunter Steven Vogt of the University of California, Santa Cruz (UCSC).

“The discovery of potentially habitable nearby worlds may be just a few years away,” he added.

Vogt and Paul Butler of the Carnegie Institution of Washington led the international team, which found the new planet systems by combining data gathered with the 10-meter Keck I telescope in Hawaii and the Anglo-Australian Telescope in New South Wales, Australia. The astronomers describe the new planetary systems in two papers that will appear in the Astrophysical Journal.

One of the new systems orbits the bright star 61 Virginis, which can be seen with the naked eye under dark skies in the spring constellation Virgo. This particular star, which is 28 light-years from Earth, stands out among hundreds of close stellar neighbors as being one of the best twins of the Sun in terms of age, mass and other properties. Vogt and his collaborators discovered at least three planets orbiting 61 Vir. They range in mass from roughly five to 25 times the mass of Earth and orbit the star in four, 38 and 124 days.

The second new system the team identified features a 7.5 Earth-mass planet orbiting HD 1461, another near-perfect solar twin located 76 light-years away. Lying in the constellation Cetus, HD 1461 can be seen with the naked eye in the early evening under dark-sky conditions. At least one planet orbits the star and two others are strong candidates.

The 7.5-Earth-mass planet, HD 1461b, has a mass nearly midway between the masses of Earth and Uranus and a period of 5.77 days. The researchers cannot tell yet whether HD 1461b is a scaled-up version of the Earth, composed largely of rock and iron, or whether it is similar to Uranus and Neptune and composed mostly of water.

The 61 Vir and HD 1461 planet detections add to a slew of recent discoveries that suggest that planets orbiting the Sun’s nearest neighbors are extremely common, and about half of all nearby stars have a detectible planet with mass equal to or less than Neptune’s, Butler said.

He explained that the new detections required state-of-the-art instruments and detection techniques. “We’ve found there is a tremendous advantage to be gained from combining data from the AAT and Keck telescopes, two world-class observatories,” he said. “It’s clear that we’ll have an excellent shot at identifying potentially habitable planets around the very nearest stars within just a few years.”

Currently, the inner planet orbiting the 61 Vir system has one of the lowest-amplitude planetary signals that have been identified with confidence, which means it is one of the more difficult planets to detect because it is so small, Butler added.

Based on extensive numerical simulations, a habitable Earth-like world could easily exist in the unexplored region between the newly discovered planets and the outer dust disk of 61 Vir, said Eugenio Rivera, lead author of one of the papers and a postdoctoral researcher at UCSC.

The team uses radial velocity measurements taken with Keck Observatory’s High Resolution Echelle Spectrometer, or HIRES, to detect a “wobble” induced in the star’s spectrum by the gravitational tug of an orbiting planet. This technique is coupled with photometric monitoring of the star to detect the transit of a planet in front of the star.

With improvements in the equipment and observing techniques, these ground-based methods are now capable of finding Earth-mass objects around nearby stars, said research collaborator Gregory Laughlin, also of UCSC.

“It’s come down to a neck-and-neck race as to whether the first potentially habitable planets will be detected from the ground or from space,” he said. “A few years ago, I’d have put my money on space-based detection methods, but now it really appears to be a toss-up. What is truly exciting about the current ground-based radial velocity detection method is that it is capable of locating the very closest, potentially habitable planets.”

The Anglo-Australian Telescope is a 3.9 meter telescope located at Siding Spring Observatory near Coonabarabran, Australia and is operated jointly by the United Kingdom and Australia.

This research was supported by the National Science Foundation and NASA. The Lick-Carnegie Exoplanet Survey Team has developed a publicly available tool, the Systemic Console, which enables members of the public to search for the signals of extrasolar planets by exploring real data sets in a straightforward and intuitive way. This tool is available online at http://www.oklo.org.

Keck Observatory’s Interferometer takes closer look at supermassive black holes

December 8, 2009

MAUNA KEA, HI—Astronomers at the W. M. Keck Observatory are using a technique called interferometry to provide new information about central black hole systems in galaxies.

Makoto Kishimoto, of the Max Planck Institute for Radio Astronomy in Bonn, Germany, and an international team of collaborators successfully observed four active galactic nuclei systems with the Keck Interferometer in May 2009. For the first time, the team resolved a QSO (or quasi-stellar object), an energetic galaxy with an active galactic nucleus that lies at a distance of more than a billion light years from Earth.

Being able to observe the central accreting material in such a distant object is “due to the huge effort of the Observatory staff to improve the sensitivity of the Keck Interferometer,” said Kishimoto. The team also made follow up observations of the target galaxies with the United Kingdom Infrared Telescope. The results appear in the December issue of Astronomy & Astrophysics.

The active cores of galaxies are thought to be powered by accreting supermassive black holes. Many cores show very intense radiation across the electromagnetic spectrum. Sometimes the nucleus exhibits a central jet in radio wavelengths, while the black hole’s accreting gas and dust are especially strong in the optical and infrared wavelengths.

Using the intense light coming from the active nuclei of galaxies, astronomers want to “directly see what exactly is going on in the vicinity of accreting supermassive black holes, how the black hole is eating up the surrounding gas, and how the strong jet is being launched,” Kishimoto, the paper’s lead author, said.

But to observe such a distant object sharply enough in infrared wavelengths requires the use of a telescope having a diameter of 100 meters or more. Instead of building such a large telescope, which is currently impossible, a more practical way is to combine the light from two or more telescopes that are roughly 100 meters apart, he explained. This type of instrument, called a long-baseline interferometer, is possible with Keck.

The twin 10-meter Keck telescopes are separated by a distance of 85 meters and are routinely used as an interferometer. When the telescopes work together, astronomers are able to detect an interference pattern to infer what the black hole vicinity looks like, Kishimoto said.

In 2003, astronomer Mark Swain of the Jet Propulsion Laboratory (JPL) along with the Keck Interferometer development team from JPL and Keck Observatory used the interferometer to observe the material accreting around a supermassive black hole called NGC 4151. The observations provided the first direct clue of the inner region of a supermassive black hole system, said Robert Antonucci of the University of California, Santa Barbara and coauthor on the new paper.

“The results looked puzzling in 2003. But with the new data and with more external information, we are quite sure of what we are seeing,” Kishimoto said. According to the team’s results, the Keck interferometer has just begun to resolve the outer region of an active galactic nucleus’s accreting gas where co-existing dust grains are hot enough to sublimate, or transition directly from a solid to a gas, he explained.

Using independent measurements of the radius of the dust sublimation region—which come from the analysis of the variability of the optical and infrared light—the astronomers have started to probe how the accreting material is distributed away from the black hole, Kishimoto said.

Being able to isolate and study the light from extremely close to the black hole itself, where the matter is actually being “swallowed,” lets “us see gas clouds less than a light year from a supermassive black hole, helping us to figure out just how a black hole obtains its ‘food’,” Antonucci said.

These observations, and even more sensitive ones of the future, provide astronomers with a more detailed understanding of how a galaxy’s central black hole system works, Kishimoto said.

First of its kind superbright supernova

December 2, 2009

Berkeley, Calif. – A discovery of an extraordinarily bright, extraordinarily long-lasting supernova named SN 2007bi turns out to be the first known example of the earliest types of stars that populated the Universe. The unusually luminous supernova could provide astronomers with clues about the earliest stars in the cosmos and could be the first of many similar events soon to be discovered.

SN 2007bi was found in 2007 by the Nearby Supernova Factory (SNfactory) based at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory. Over the next 18 months, observations of the exploding star were made by an international team of astronomers using the 10-meter Keck I telescope on the summit of Mauna Kea in Hawai’i and the Very Large Telescope in Chile.

Based on the data, the team determined that SN 2007bi was the explosion of an exceedingly massive star, said astronomer Alex Filippenko of the University of California Berkeley whose group helped obtain, analyze and interpret the data. “But instead of turning into a black hole like many other heavyweight stars, its core went through a nuclear runaway that blew it to shreds. This type of behavior was predicted several decades ago by theorists, but never convincingly observed until now.”

According to the data, which was collected in a collaboration led by Avishay Gal-Yam of Israel’s Weizmann Institute of Science, the supernova’s precursor star could only have been a giant having at least 200 times the mass of the Sun and initially containing few elements besides hydrogen and helium – a star similar to the first stars in the early Universe.

SN 2007bi is also the first confirmed observation of a pair-instability supernova. The long-hypothesized phenomenon suggests that “in the extreme heat of the star’s interior, energetic gamma rays created pairs of electrons and positrons, which bled off the pressure that sustained the core against collapse,” said astrophysicist Peter Nugent, co-leader of Berkeley Lab’s Computational Cosmology Center (C3), a collaboration between the Lab’s Physics Division and Computational Research Division, or CRD.

The researchers describe the data to support the pair instability supernova finding in the Dec. 3 issue of Nature.

On the trail of a strange beast

SN 2007bi was first recorded on images taken as part of the Palomar-QUEST Survey, an automated search with the wide-field Oschin Telescope at the California Institute of Technology’s Palomar Observatory, and was quickly detected and categorized as an unusual supernova by the SNfactory. The SNfactory has so far discovered nearly a thousand supernovae of all types and amassed thousands of spectra, but has focused on those designated Type Ia, the “standard candles” used to study the expansion history of the Universe.

“The thermonuclear runaway experienced by the core of SN 2007bi is reminiscent of that seen in the explosions of white dwarfs as Type Ia supernovae, but on a much larger scale and with a far greater amount of power,” Filippenko said. SN 2007bi was at least ten times as bright as the standard Type Ia supernovae.

Rollin Thomas of CRD, a member of C3 and the SNfactory, used the Franklin supercomputer at the National Energy Research Scientific Computing Center to match synthetic supernovae spectra with the real SN 2007bi spectrum. The model fit was unambiguous: SN 2007bi was a pair-instability supernova.

“The central part of the huge star had fused to oxygen near the end of its life, and was very hot,” Filippenko explained. “Then the most energetic photons of light turned into electron-positron pairs, robbing the core of pressure and causing it to collapse. This led to a nuclear runaway explosion that created a large amount of radioactive nickel, whose decay energized the ejected gas and kept the supernova visible for a long time.”

A fossil laboratory of the early Universe

Finding the first unambiguous example of a pair-instability supernova in a dwarf galaxy is significant, Nugent said. Dwarf galaxies are incredibly small and dim and contain few elements heavier than hydrogen and helium, so they are models or fossil laboratories of the early Universe. Dwarf galaxies are also ubiquitous, but, they are so faint and dim that they’ve rarely been studied. SN 2007bi is expected to focus attention on these fainter galaxies.

Studying the dwarf galaxies and their remnant supernovae might, in the future, allow astronomers to— through explosions such as that of SN 2007bi— “detect the very first generation of stars, early in the history of the Universe, long before we have the capability of directly seeing the pre-explosion stars,” Filippenko explained. So while SN 2007bi is the first of its kind to be detected, it is likely not the last.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for the Department of Energy’s Office of Science and is managed by the University of California. For the full release, visit http://newscenter.lbl.gov/.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

A Galactic “fossil” in the core of the Milky Way

November 25, 2009

KAMUELA, HI—Astronomers using the W. M. Keck Observatory and the European Southern Observatory’s Very Large Telescope have identified two distinct groups of stars within the Milky Way Galaxy’s globular cluster Terzan 5. The two stellar populations have different ages and iron abundances, which are rare features among globular clusters, suggesting that Terzan 5 could be a surviving remnant of pre-existing galaxy.

Orbiting the Milky Way’s Galactic Center, Terzan 5 is among the brightest star clusters and would easily be seen through binoculars were it not for the veil of dust between the Earth and this cluster. It was thought to be a “common” globular cluster, a compact population of stars bound by gravity with the same age and chemical composition. The new observations of this cluster, published in the Nov. 26 issue of Nature, demonstrate that Terzan 5 is not a genuine globular cluster but is the remnant of a proto-galaxy that merged with similar systems to form the Galactic bulge.

This discovery opens a new window on the formation mechanisms of galaxies and could be the first observational evidence to confirm that the bulge of a galaxy originates from the merging of pre-formed, internally evolved systems of stars, said the study’s lead author, Francesco Ferraro of the University of Bologna in Italy.

Ferraro and his colleagues studied Terzan 5, which is located in the central bulge of the Galaxy—a region that has been hard to study because of its high concentration of interstellar dust. Yet, the astronomers were able to identify two, distinct stellar populations—a bright one whose stars are centrally concentrated and a second one, whose stars are fainter—within Terzan 5.

Spectral data taken with the Keck II telescope and its NIRSPEC instrument also demonstrated that the brighter branch is roughly three times richer in metals, specifically, iron, which is formed in supernovae, said team member R. Michael Rich, of the University of California at Los Angeles.

“This new population is in fact among the most metal rich stars that we know of; it’s kind of like finding a buried treasure in this unusual star cluster,” said Dr. Livia Origlia of the Bologna Observatory, who discovered the iron-rich stars.

Astronomers have not previously observed such an anomaly in a Galactic Globular Cluster. The Milky Way has roughly 150 globular clusters, and, until now, omega Centauri was the only stellar system where distinct stellar populations with different iron content and age have been detected. This suggests it is the remnant of a disrupted dwarf galaxy that merged with the Milky Way late during its evolution. The striking peculiarity of Terzan 5 is that its oldest population has the same metal content as the most metal rich bulge stars. This strongly suggests that it is the relic of a building block of the Bulge: similar stellar systems would have merged together to finally form the Bulge during the early epoch of galaxy assembly.

Modeling the differing ages and abundances of metals among the star population in the Terzan 5 cluster suggests the entire cluster experienced a second burst of star formation six billion years after the initial burst, Ferraro said.

The models also suggest that ejecta of supernova explosions are the likely source of the heavier elements within the metal rich, bright star population of Terzan 5. Supernova ejecta, however, can only remain in systems much more massive than the current globular clusters. Therefore, we surmise that Terzan 5 is very likely to be yet another tattered relic of a pre-existing galaxy that was shredded and engulfed by the Milky Way, and the dust-obscured central region of the Galaxy may harbor many more similar objects, Ferraro added.

The European Southern Observatory operates the Very Large Telescope, made up of four separate 8.2 meter optical telescopes located in the Atacama desert in northern Chile.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The telescopes feature a suite of advanced instrumentation including NIRSPEC, a near infrared echelle spectrograph commissioned on the Keck II telescope in 1999. NIRSPEC was constructed by the UCLA Infrared Laboratory, which celebrated its 20th anniversary on November 20, 2009. Keck Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

Rapid supernova could be new class of exploding star

November 9, 2009

BERKELEY, CA—An unusual supernova rediscovered in seven-year-old data taken at the W. M. Keck Observatory and Lick Observatory may be the first example of a new type of exploding star, possibly in a binary star system where helium flows from one white dwarf onto another and detonates in a thermonuclear explosion.

In a paper first published online Nov. 5 in Science Express, astronomer Dovi Poznanski, of the University of California, Berkeley (UCB) and Lawrence Berkeley National Laboratory (LBNL), and his colleagues describe supernovae SN 2002bj and review the data that suggest it is a new type of stellar explosion.

The supernova was detected in 2002 in the galaxy NGC 1821, in the constellation Lepus, by UC Berkeley astronomer Alex Filippenko’s Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory near San Jose, as well as by amateur astronomers. The exploding star’s spectrum was obtained seven days after its discovery using the Keck I telescope with its Low Resolution Imaging Spectrograph.

The supernova was erroneously classified by the astronomical community as a common Type II supernova and filed away.

In June 2009, Poznanski reanalyzed the spectrum while reviewing data of Type II supernovae, which he wants to use as distance indicators to confirm the accelerating expansion of the Universe. When he carefully examined a high-quality spectrum of SN 2002bj, he realized that the supernova was not a Type II at all, but an unusual kind of supernova more akin to a Type Ia.

According to follow-up images made by KAIT, SN 2002bj disappeared 20 days after its discovery. An image of that area of the sky taken seven days prior to its discovery showed no supernova, so it had brightened and dimmed into obscurity in less than 27 days. Most supernovae brighten and dim over three to four months.

“This is the fastest evolving supernova we have ever seen,” said Poznanski, a UC Berkeley post-doctoral fellow who recently joined LBNL’s Computational Cosmology Center. “It was three to four times faster than a standard supernova.”

This rapid drop, coupled with the supernova’s faintness, the strong signature of helium in the spectrum of the explosion, the absence of hydrogen, and the possible presence of vanadium – an element never previously identified in supernova spectra – points toward helium detonation on a white dwarf.

“We think this may well be a new physical explosion mechanism, not just a minor variation of ones already known,” said Filippenko, a coauthor on the study. “This supernova is qualitatively different from the complete disruption of a white dwarf, known as a Type Ia supernova, or the collapse of an iron core and rebound of the surrounding material, so-called ‘core-collapse supernovae.’”

Co-author Joshua Bloom, of UCB, added that astronomers have seen great diversity in those two main supernova mechanisms, “but even within that diversity, observationally, there is a limited range of variation spectrally and in how events evolve in time,” he said. “This object (SN 2002bj) falls outside that range.”

Based on the available images and spectra SN 2002bj, Poznanski and graduate student Ryan Chornock – now a post-doctoral fellow at Harvard University – determined that the theory involving AM Canum Venaticorum (AM CVn) binary systems best matches the data.

Proposed by Lars Bildsten, a professor of physics at the Kavli Institute for Theoretical Physics at UC Santa Barbara, and colleagues, the theory of AM CVn binary systems describes them as composed of two white dwarfs, one of which is primarily made of helium that is being slowly pulled by gravity onto its companion. White dwarfs are the remnants of stars that burned their hydrogen down to carbon and oxygen or, in some particular cases, to helium.

In a 2007 Astrophysical Journal Letters paper, Bildsten and colleagues proposed that in AM CVn systems, when enough helium has been accumulated on the surface of the primary white dwarf, an explosion will occur that can “power a faint … and rapidly rising (few days) thermonuclear supernova.” The event is now called a .Ia (point one A) supernova, because it is one-tenth as bright for one-tenth the time as a Type Ia supernova.

Filippenko added, however, that this explosion is nothing like a regular Type Ia explosion because the white dwarf survives the detonation of the helium shell. In fact, it has similarities to both a nova and a supernova. Novas occur when matter – primarily hydrogen – falls onto a star and accumulates in a shell that can flare up as brief thermonuclear explosions. SN 2002bj is, however, a “super” nova because it generated about 1,000 times the energy of a standard nova, he said.

The past few years have yielded a bonanza of weird supernovae, Filippenko said. “A lot of us who have studied supernovae for several decades are amazed at the quality and quantity of data coming in recently, showing interesting new subclasses or even strange new physical classes of supernovae,” he said. “It whets my appetite for what else we might find out there.”

A New View of the Moon

October 9, 2009

KAMUELA, HI—On Oct. 9, astronomers at the W. M. Keck Observatory used the Keck II telescope to search for water harbored in the Moon’s permanently shadowed craters.

The observations were made as part of the Observatory’s participation in NASA’s Lunar Crater Observation and Sensing Satellite, or LCROSS, mission. At 1:31 and 1:35 a.m. Hawaii Standard Time, two LCROSS impactors collided with the crater Cabeus on the South Pole of the Moon.

Diane Wooden of the NASA Ames Research Center in Moffett Field, Calif. used Keck II with its Near Infrared Echelle Spectrograph, or NIRSPEC, to analyze the resulting ejecta plume for the chemical signature of water vapor.

It is the first time that astronomers could use features on the Moon’s surface to properly position the Keck II telescope to take spectroscopic observations and images of the lunar surface. NIRSPEC’s upgraded guide camera and improved guiding software, which are part of the Observatory’s program called MAGIQ, or Multi-function Acquisition, Guiding, and Image Quality, monitoring system, made the spectroscopic observations possible and took the images.

Wooden and the other LCROSS astronomers are currently evaluating the spectroscopic data collected at Keck and the other Mauna Kea observatories for the water vapor signature. The team plans to report the results soon.

Keck Interferometer Nuller Spots Double Dust Cloud

September 24, 2009

KAMUELA, Hawaii (Sept. 24, 2009) — Linking the twin, 10-meter telescopes in Hawaii, astronomers at the W. M. Keck Observatory discovered an extended, double-layered dust disk orbiting 51 Ophiuchi, a star that is 410 light-years from Earth. It is the first time the Keck Interferometer Nuller instrument has identified such a compact cloud around a star so far away.

The new data suggest that 51 Ophiuchi is a protoplanetary system with a dust cloud that orbits extremely close to its parent star, said University of Maryland astronomer Christopher Stark, who led the research team.

Keck Observatory operates one of the largest optical interferometers in the United States. The interferometer provides high precision resolution measurements equal to a telescope as large as the distance that separates the telescope’s primary mirrors—85 meters in the case of the Keck twins. In April 2007, the team simultaneously pointed both Keck telescopes at the star 51 Ophiuchi, or 51 Oph, and used the Interferometer’s Nuller, a technique to combine the incoming light in a particular way, to block the unwanted starlight of 51 Oph and measure faint adjacent signals from the dust cloud surrounding the star.

According to the observations, excess material orbited 51 Oph. Stark and his collaborators repeated the nulling measurements at several different wavelengths of light and combined this data with information from other telescopes to determine the shape and orientation of the material as well as the sizes of the dust grains.

The data suggest that two debris disks orbit 51 Oph. The inner disk has larger grains, roughly 10 micrometers or larger in diameter, and extends out to four astronomical units, or AUs, beyond the star. The second disk comprised of mainly 0.1 micrometer grains extends from roughly seven AU to 1200 AU. One AU is the distance between Earth and the Sun or roughly 93 million miles. The new results appear in the Oct. 1 Astrophysical Journal.

If these debris disks orbited the Sun, the inner cloud of larger grains would extend roughly from the position of Mercury’s orbit to just past the edge of the asteroid belt. The outer disk of smaller grains would originate just before Saturn’s orbit and extend to a distance ten times farther than the edge of the Kuiper belt.

51 Oph’s inner, compact dust disk is one of the most compact dust clouds ever detected, and the new Keck Interferometer Nuller observations demonstrate the instrument’s ability to detect dust clouds a hundred times smaller than a conventional telescope can observe, Stark said.

The instrument was also essential to solving the mystery of what made 51 Oph’s dust disk appear so compact while its spectra, or chemical fingerprints, suggested that the dust orbited at much larger distances, added Marc Kuchner, an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Md. who was part of the research team. The answer was simply that the star had two debris disks.

Because of the power of the Keck Nuller, Stark and his team were able to resolve inner and outer dust disks, which together form 51 Oph’s exozodiacal cloud. In similar star systems, the outer cloud of dust seems to be a distinct outer belt, probably analogous to the Kuiper belt or a second system of asteroids. But 51 Oph appears to be different, Kuchner said. The observations suggest that the star’s outer cloud is comprised of smaller grains and is connected to the inner cloud so that the system has only one underlying belt of asteroids.

This system most likely represents a rare, nearby example of a young planetary system just entering the late stages of planet formation. Terrestrial planets may be forming, although none have been detected within the system yet, Stark said.

His team’s data also indicates that the cloud around 51 Oph is 100,000 times more dense than the dust cloud circling the Solar System. In most planet-forming systems, as asteroid and comet collisions produce dust, the larger grains spiral toward the star while its outward pressure pushes smaller particles to the edge or even out of the system. 51 Ophiuchi, a star 260 times more luminous than the Sun, likely pushes the smaller dust grains from the inner disk to the outer disk, Kuchner explained.

Keck’s Nuller, which was funded by NASA, will be used to help astronomers further understand how and when these asteroid belts form and how dust from the star’s debris disk might interfere with direct imaging of planets orbiting another star, he said.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and a world-leading laser-guide-star adaptive optics system. The Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

Jupiter Adds a Feature

July 20, 2009

Mauna Kea, Hawai’i—Jupiter’s got a brand new mark. Something slammed into the gas giant leaving a dark bruise in the planet’s atmosphere, scientists at Keck Observatory confirmed early on the morning of July 20 Hawaiian Standard Time.

The observation, made with the Keck II telescope, marks only the second time astronomers have seen such an impact on the planet. The first collision occurred 15 years ago, when more than 20 fragments of comet Shoemaker-Levy 9 (SL9) collided with Jupiter.

The SL9 impact events were well-studied in 1994, and many theories were subsequently developed based on the observations. “Now we have a chance to test these ideas on a brand new impact event,” said Paul Kalas, one of the University of California Berkeley (UCB) astronomers who helped observe the latest impact.

Kalas, along with Michael Fitzgerald of Lawrence Livermore National Lab and UCLA, happened to have observing time on the Keck II telescope early on the morning of Monday July 20, 2009. The two were searching for the Jupiter-like planet, Fomalhaut b, which orbits the star Fomalhaut. The star is located roughly 25 light years from Earth in the direction of the constellation Piscis Austrinus.

The astronomers decided to observe Jupiter after hearing of Australian amateur astronomer Anthony Wesley’s discovery of the planet’s new feature, which they read about on the blog of UCB and SETI Institute astronomer Franck Marchis. Together, the group of UC astronomers collaborated on how best to make the observations of the new feature. Fitzgerald then performed the observations with the help of Keck Observatory astronomer Al Conrad.

“The fact that [the feature] shows up so clearly means that it’s associated with high-altitude aerosols as seen in the Shoemaker-Levy impacts,” noted James Graham of UCB, who also assisted with the new observations as well as the observations taken during the SL9 event in 1994. According to the new data, an impact must have created Jupiter’s latest feature, the team of astronomers said.

New Method Finds Most Distant Supernovae

July 8, 2009

Mauna Kea, Hawai’i—Astronomers have yet again rewritten the record books for discovering the most distant supernovae. Using Hawaii’s W. M. Keck Observatory and Canada-France-Hawaii Telescope (CFHT), a team has identified remnants of two massive stars that exploded roughly 11 billion years ago.

Studying the deaths of these early stars is essential to understanding the evolution of the Universe and how its elements were formed and distributed to create later stars and even planets, said cosmologist Jeff Cooke of the University of California, Irvine.

He added that while the newly identified explosions may be the farthest of any supernovae type found to date, the innovative method developed to identify the explosions should make it possible to discover even more distant supernovae—possibly even a few of the very first stars to blow themselves apart.

Cooke developed this new method to study the explosive death of stars that are 50 to 100 times the mass of the Sun. The progenitor stars of this kind of supernovae, the type IIn, are distinct because they shed most of their material into the cosmos just before they die. When the stars finally explode, they spew out their remaining material, which ploughs into the previously expelled gas. The collisions make the entire stellar remnant so bright that its glow can still be detected many years after the star’s demise.

To find the most distant of these supernovae, the astronomers examined archival data from the CFHT Legacy Survey to identify four, extremely distant objects that appeared to brighten and then fade over time, resembling distant supernovae. Cooke, who led the team, explained that cosmologists typically identify supernovae by comparing nightly images of the same patch of space taken at regular intervals throughout the year. The images show several hundred to thousands of galaxies, and a slight increase in the amount of light in any one of the galaxies in one image compared to the previous image may indicate a star has blown apart and died.

Using this knowledge, the astronomers stacked and blended a year’s worth of CFHT images taken of the same, dark patch of sky and did this for four separate years. Stacking the images into one composite enable the team to detect fainter objects and thereby probe farther back in the Universe. “It’s like in photography when you open the shutter for a long time. You’ll collect more light with a longer exposure,” Cooke said.

By comparing composite images over the four years, Cooke’s team identified four potential supernovae. The astronomers then used the Low Resolution Imaging Spectrograph (LRIS) on the Keck I telescope and the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope to analyze the spectrum of light that each object emitted to determine the objects’ composition and distance. The data showed that the light from the supernovae had traveled nearly 11 billion light years to reach Earth. Both the results and the new method appear in the July 9 edition of Nature.

Cooke’s technique is “powerful and reliable,” because “it’s simple, clean and the results are unambiguous. In retrospect, I can’t believe we haven’t capitalized on this method sooner,” said astronomer Alicia Soderberg, who studies supernovae at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. and was not involved in the study. The technique will revitalize research on this kind of supernovae and will provide astronomers with a much-needed process to probe the deaths of some of the earliest stars in the Universe, she added.

Prior to this discovery, astronomers’ records showed that the most distant supernova of this type exploded roughly six billion years ago, and the most distant of any supernovae type exploded roughly nine billion years ago. Cooke said that by studying extremely distant supernovae, astronomers will better understand where stars were exploding just after the Big Bang and how stellar properties change as the Universe evolved. And, because stars form heavier and heavier elements in their core, the technique might also give astronomers a glimpse of how the elements essential to planet formation and to the existence of life were initially created and distributed throughout the cosmos.

“This new method could not have been published at a better time,” Soderberg said, explaining that many large survey telescopes, such as the Large Synoptic Survey Telescope, will soon be online to identify thousands of candidate supernovae. Astronomers can then use large eight to ten meter telescopes, such as Keck, to obtain the necessary deep spectra of the supernovae to determine their distance and the abundance of elements that they spew into space after they explode.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and a world-leading laser-guide-star adaptive optics system. The Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

The research was funded by the National Science Foundation and by generous support from Gary McCue to the Center for Cosmology at UCI.

Enceladus shows little sodium leaving scientists questioning existence of underground ocean

June 24, 2009

One of Saturn’s moons, Enceladus, appears to be missing some sodium. The new observations made at the W. M. Keck Observatory suggest that the plumes of gas and ice seen exploding from the moon are not fueled by geysers erupting from a salty ocean just beneath Enceladus’ surface. The conclusion has left scientists uncertain about the tiny moon’s interior.

“We really expected to see sodium in the data giving evidence right then and there of a possible ocean on Enceladus,” said astronomer Mike Brown of the California Institute of Technology. To the astronomers’ surprise, no spectral feature appeared in the data.

The team of international astronomers, led by Nick Schneider of the University of Colorado, used the High Resolution Echelle Spectrometer, or HIRES, at Keck Observatory to analyze the sunlight reflected by Enceladus. The calculated upper limit of sodium present in the moon’s vapor plume was 30 times lower than expected, the astronomers report in the June 25 Nature.

Observing little to no sodium in the plume vapor and ice grains erupting from the southern pole of Enceladus is “quite surprising” because other, less active bodies in the Solar System have sodium signatures that are much easier to distinguish, said planetary scientist John Spencer of the Southwest Research Institute in Boulder, Co., who was not involved in the study.

Sodium atoms are among the most easily detected and most common elements in the Solar System. Their non-existence in the Enceladus’ jets suggests the moon is very different from Jupiter’s moons Io and Europa, the Moon and Mercury, which all show sodium signatures in their thin atmospheres, Brown added.

The vapor and ice particles found in the jets are also thought to be the source of Saturn’s outermost ‘E’ ring. The jets, and salt in the ring, could therefore be coming from a much deeper, salt-based ocean. Brown said that deep caverns might allow water to evaporate slowly, which would mean it would contain little sodium—much like water evaporating from Earth’s oceans. The vapor could turn into a jet because it would leak out of fractures in the moon’s icy crust and then into the vacuum of space.

The scenario is possible, but the new observations could also mean that the low-salt vapor escaping from Enceladus comes from evaporation of a low-salt, liquid reservoir or from warm ice sublimation—the transition from solid to gas with no liquid phase, Brown explained. The plume could also originate from the decomposition of molecular cages called clathrates, which might release small amounts of sodium.

“In essence, we still don’t understand the origin of the ice and vapor jets and therefore how the salt particles get into space,” he added.

Enceladus is a “very different beast,” and theorists need to do more work to understand how vapor and ice grains form inside Enceladus and then get out to the ‘E’ ring, Spencer said.

“Basically, this result shows we don’t really know what’s going on within this little moon. It also shows us that ground-based telescopes, such as Keck, are essential to Solar System studies,” Brown said. “Now we astronomers have to put our heads together to figure out how we are going to learn more about Enceladus.”

The W. M. Keck Observatory operates twin 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The two telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and a world-leading laser-guide-star adaptive optics system. The Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

Exoplanet’s tilted orbit challenges theories of planet formation

June 24, 2009

An international team of astronomers has discovered an exoplanet whose orbit is steeply tilted from the plane of the star’s equator, a finding that contradicts theories about how planetary systems form.

The new observations conducted at the W. M. Keck Observatory in Hawaii provide a clear, solid measurement of the planet’s distinctive tilt, determining the angle of the orbit to be about 37 degrees from the star’s equator. The results appear in the online edition of the Astrophysical Journal and will be published in an upcoming August issue.

Astronomers discovered the planet, called XO-3b, because it passes directly in front of the star as seen from Earth - an event called a transit - thus causing a slight dimming of the star’s light. That dimming can be detected with a powerful telescope connected to a highly sensitive light meter, or photometer. Of the more than 350 exoplanets discovered so far, fewer than two dozen have been discovered through this transit method.

Detecting the planet itself was relatively easy, as it dimmed the star’s light by about one percent. But to go one step further and measure the angle of its orbit, even with such powerful tools, means that “we have to be sneaky about it,” said physicist and the paper’s lead author Joshua Winn of the Massachusetts Institute of Technology in Cambridge, Mass.

He explained that if a planet crosses the star’s disk at an angle relative to the star’s rotation, it causes a distinctive pattern that changes the overall color of the star, as measured by a highly sensitive spectrograph. In this study, astronomers John Asher Johnson of the University of Hawaii and Andrew Howard of the University of California Berkeley (UCB) used the Keck I telescope’s High Resolution Echelle Spectrometer, or HIRES, to confirm hints of such a spectral signature, which another team observed but could not verify last year.

Observing a misalignment of the planet’s orbit relative to the star’s equator is a “remarkable result,” and completely contradicts simple theories of planet formation, said astronomer and paper coauthor Geoff Marcy of UCB.

“In all models of planet formation, a young star is surrounded by a flattened disk of gas and dust, like a fried egg with the yellow yolk, the star, in the middle and the white, the gas and dust, extending outward from the equator of the ‘yolk’,” he explained.

The planets form by collecting the dust and gas together within that disk. The theories naturally explain how the planets in the Solar System reside in a flat plane that slices through the equator of the Sun. Other planetary systems show a similar architecture.

“What is shocking about this planetary system is that the planet orbits in a plane that is grossly misaligned with its star’s equator,” Marcy said.

XO-3b, is about 13 times as massive as Jupiter, yet orbits its star with a period, or “year,” of just 3.5 days. Jupiter, by contrast, takes almost 12 years to make one orbit. The planet is considered a “hot Jupiter,” meaning it resembles the Solar System’s largest planet yet is much hotter due to its proximity to its parent star.

The planet, as with all hot Jupiters, most likely didn’t form at its current orbit, but rather formed much farther out from the star, then migrated inward to its present position. Planet formation theory suggests the gravitational attraction of other planets as well as debris in the disk might tug on planets, slightly disrupting their orbit. Close encounters between or among planets, however, has enough force to significantly change the planet’s trajectory.

In the case of XO-3b, it seems “some other planet gravitationally yanked on this poor planet, jerking it out of its original circular orbit,” Marcy said. It “suffered from a gravitational close encounter. It survived, but was left in a wacky orbit.”

Astronomers are interested in exploring exoplanets, especially oddballs such as XO-3b, to help refine theories of planetary formation and to understand the kinds of variations that may be possible in the Universe. Astronomers want to “see how the dice get rolled in other planetary systems,” Winn said.

NASA’s recently launched Kepler Mission will help astronomers discover increasing numbers of exoplanets, he explained. The Keck telescopes will then be used to follow-up the space-based observations to learn more about the planets’ masses and orbits.

By discovering and observing more oddball exoplanets, astronomers will determine how often planets suffer from close encounters. And, if a large number of exoplanets are observed to have tilted orbits, scientists might be able to conclude that close encounters are common during the young lives of planets, Marcy said.

The XO-3b work was funded by the NASA Origins program, an NSF postdoctoral fellowship and World Premier International Research Center Initiative.

Keck Laser Helps Astronomers Probe the Nature of Massive Galaxies in the Early Universe

June 9, 2009

PASADENA, Calif.—Astronomers using the W. M. Keck Observatory have discovered distant galaxies as massive as the Milky Way yet ten to 1000 times more compact. The new results, announced June 9 at the 214th American Astronomical Society meeting in Pasadena, provide astronomers with surprising clues about early star and galaxy formation at a time when the Universe was just a few billion years old.

“The shapes of these galaxies tell us that it is not reasonable to expect they could occur from mergers. Instead, the kind of disks we’re seeing and the constituent stars seemed to have formed all at once, directly from the gas. In the old lingo, this is monolithic galaxy formation,” said astronomer Alan Stockton of the University of Hawai’i.

He and his colleagues Dr. Gabriela Canalizo of the University of California, Riverside and Dr. Elizabeth McGrath of the University of California, Santa Cruz used the Keck II telescope and its Laser Guide Star Adaptive Optics, or LGSAO, to image radio galaxies and quasars that are roughly 11 billion light years from Earth.

The Keck LGSAO system uses a powerful laser to excite sodium atoms in the upper atmosphere so that they emit light and appear as an artificial star. Astronomers use this artificial starlight to analyze how the atmosphere is distorting incoming light from their target astronomical sources. The distortion can then be corrected using a compensating distortion in a deformable mirror in the adaptive optics system.

From these AO-corrected observations of distant galaxies, Stockton and his colleagues could model the detailed structures of their target galaxies, which are quite unlike those of massive galaxies in the present-day Universe. The team found the objects had masses that were a hundred billion times the mass of the Sun, yet were compact and have diameters of roughly 3,000 to 15,000 light years. By comparison, the diameter of the Milky Way is 100,000 light years, yet it has a mass of about 500 billion solar masses.

Teams using the Hubble Space Telescope have also found that high redshift galaxies tend to be more compact than astronomers expected. Stockton said his team was able to obtain near-infrared images from the ground that were almost two times sharper than those they could obtain with the Hubble Space Telescope at similar wavelengths. These Keck LGSAO images allow not only the measurement of characteristic sizes of the distant galaxies, but also more detailed properties of the light distribution that may give clues to formation processes.

For example, Stockton’s team imaged a field of five galaxies two of which show a tidal tail (Fig. 2) that would be indistinguishable with Hubble. “The tail, however, can only form if the galaxies we observe were disk galaxies,” Stockton said. “This Keck data gives us further evidence of that conclusion.”

Astronomers expected that distant galaxies might be disk galaxies and would be more compact than today’s galaxies. They did not expect the galaxies to be as dense as Stockton’s observations indicate, and researchers have not yet identified objects in the local Universe that resemble these compact disk galaxies. This is surprising because dense, disk-like objects are like cannon balls and are therefore not easily destroyed by collisions, meaning some should survive today.

“It might therefore be possible that these disk galaxies have instead become the cores of today’s galaxies,” Stockton said.

The data cannot yet answer this or other questions about the morphology and evolution of these two billion-year-old galaxies. Stockton said that he is currently trying to obtain clearer spectral data of the distant galaxies to determine how fast their constituent stars are moving about their centers—this will enable astronomers to independently determine the galaxies’ masses. His team is also currently looking for examples of very compact galaxies that have survived to a

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