SPECTRUM OF YOUNG EXTRASOLAR PLANET YIELDS SURPRISING RESULTS

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 image 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

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

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.

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.

Zooming in on Infant Planetary Systems

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

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

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 http://www.facebook.com/gruberprizes.

Possible new type of supernovae puts calcium in your bones

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

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

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

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.

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.

New tidal streams found in Andromeda reveal history of galactic mergers

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.”

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.

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

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.

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.

Waltzing black holes take center stage at astronomy meeting

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.

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 telescopes take deeper look at planetary nurseries

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

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 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 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

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.

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 of its kind superbright supernova

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

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

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.”

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 New View of the Moon

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.

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.

Keck Interferometer Nuller Spots Double Dust Cloud

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

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

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

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

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.

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.

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

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 time when the Universe was half its present age, about seven billion years old. It will be possible to obtain much more detailed observations of such galaxies, which may lead to a better physical understanding of these objects. Observations to find disk galaxies at more distant redshifts will also be done to determine if disk galaxies exist in the very early Universe, Stockton said.

The Keck II telescope and its LGSAO are operated by the W. M. Keck Observatory, which manages twin ten-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 operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. For information please call 808.885.7887 or visit http://www.keckobservatory.org.

This research was supported in part by the National Science Foundation, under grant AST 03-07335.

Berkeley Astronomers Lift Shroud on Dark Gamma Ray Bursts

PASADENA, Calif.—Astronomers using the Keck telescopes may have solved the mystery of dark gamma ray bursts—intense flashes of X-ray and gamma-ray radiation that have little to no optical signature. The observations have allowed the astronomers to peer through celestial gas and dust to reveal star formation and stellar death in the dusty corners of otherwise dust-free galaxies.

“We have compelling evidence that a large percentage of star formation in the early Universe is actually hidden by dust, even inside galaxies that do not appear dusty,” astronomer Daniel Perley of the University of California, Berkeley announced June 8, 2009 at the 214th American Astronomical Society meeting in Pasadena, Calif.

Long-duration gamma-ray bursts, the most brilliant flashes of light in the Universe, are thought to originate from the explosion of massive stars. These events create two pencil-like beams of light, akin to lighthouse beacons, bright enough to be seen from as far away as 13 billion light years, which is near the edge of the observable Universe. Most gamma-ray bursts continue to shine brightly in optical light for many hours after the gamma-ray emission subsides, a phenomenon known as an ‘optical afterglow’. Yet, events with little or no detectable visible light, dubbed “dark GRBs,” have puzzled astronomers.

Some have suggested that these GRBs are so far away, and thus at such high redshift, that their optical afterglow is shifted out of the visible wavelengths and into the infrared. The new observations, however, support one other prevailing hypothesis for the existence of dark gamma ray bursts— that dust obscures the visible wavelengths of the gamma ray bursts in galaxies at less extreme distances (less than about 12.9 billion light years from Earth).

“The Perley and Bloom work is a very significant result,” said Wendy Freedman, director of the Carnegie Observatories in Pasadena, Calif. who was not involved in the research. She explained that GRBs have excited the astronomical community since their detection in the 1960s. This study is “fundamental,” she explained, because it provides information about the nature of GRBs in the early Universe. It also provides important information about the formation rate of stars when the Universe was merely 700 million years old, she added.

To draw these conclusions, the team first used the 60-inch Palomar telescope to conduct follow-up observations of 29 bursts discovered by NASA’s Swift gamma-ray satellite, 14 of which were classified as dark. The astronomers then used the Keck I telescope to look for the host galaxies of “dark” GRBs. For 11 of these 14 dark bursts, the team successfully detected a distant galaxy hosting the explosion. The remaining three bursts had faint optical counterparts.

Perley said the results indicate that none of these bursts had come from the most distant regions of the Universe since at distances greater than 12.9 billion light years the optical light would be shifted into the infrared due to the expansion of the Universe. The astronomers’ sample lacks these very high redshift events, which indicates that extremely distant explosions cannot comprise more than a few percent of all gamma-ray bursts, Perley said.

Still, such distant bursts are known to exist. Two months ago a gamma ray burst at a distance of 13.1 billion light years was discovered. Combining information from this event with the rest of the sample, the team now estimates that the fraction of high redshift GRBs is between 0.2 and seven percent.

In this study, because dim optical signatures where identified and none of the 14 bursts in the survey appear to be at a distance of more than 13 billion light years, the astronomers can conclude that the optical dimness of the bursts is due to dust inside the host galaxy. The dust absorbs light from the afterglow before it escapes. But, the starlight shows no recognizable dust signatures, which indicates that the dust may be clumped in patches or clouds where it is difficult to detect.

Consequently, there could be much more dust than has been suspected as the result of measurements using other techniques. Perley said that dark gamma-ray bursts could therefore provide a complementary way of answering the question of how much star formation is going on inside galaxies in the early Universe. The data indicate that the star formation rate in the early Universe was not as intense as previously thought. More research needs to be done to confirm this conclusion.

The team has submitted a paper about the study to The Astronomical Journal.

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 operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. For information please call 808.885.7887 or visit http://www.keckobservatory.org.

The Swift mission, equipped with a gamma-ray detector and X-ray, ultraviolet and optical telescopes, is operated by NASA’s Goddard Spaceflight Center.

Mysterious Space Blob Discovered at Cosmic Dawn

Astronomers using a suite of telescopes including the W. M. Keck Observatory have discovered a giant gas object that may be one of the earliest ancestors of a forming galaxy. This object, dubbed an extended Lyman-Alpha blob and identified as Himiko, sits nearly 13 billion light years from Earth and spans 55 thousand light years, a record for that early point in time.

“Measuring the distance to this object with Keck’s instrumentation was fundamental to making this discovery,” says Taft Armandroff, director of the Keck Observatory. “The observations show that this gigantic gaseous object formed when the Universe was only about 800 million years old, a time when astronomers have not expected to see objects like these.”

In fact, astronomer Masami Ouchi, a fellow at the Observatories of the Carnegie Institution, was not sure of what he and his colleagues were observing when they first spotted Himiko. Even with data from the world’s best telescopes, the Lyman-Alpha blob is one of the most distant objects ever found. Its distance does not easily allow researchers to understand its physical origins. The object could therefore be ionized gas powered by a super-massive black hole, a primordial galaxy with large gas accretion, a collision of two large young galaxies, super wind from intensive star formation or a single giant galaxy with a large mass of about 40 billion Suns, says Ouchi, who led the astronomers from the U.S., Japan and the United Kingdom in discovering Himiko.

“I never imagined that such a large object could exist at this early stage of the Universe’s history,” Ouchi says. “I am surprised by this discovery because according to Big Bang cosmology, small objects form first and then merge to produce larger systems.” This object spans 55 thousand light years, which roughly compares to the radius of the Milky Way. Yet, it exists at a time when the age of the Universe was only six percent of the age of today’s Universe, Ouchi explains.

He and his colleagues first discovered Himiko in the constellation Cetus using the Subaru telescope. The object was among 207 distant galaxy candidates. But it seemed extraordinarily large and bright to be far away. The team, therefore, hesitated to spend their “precious telescope time” taking spectra of this “weird candidate” because the object might be a foreground interloper contaminating the galaxy sample, Ouchi says. The astronomers decided to take the spectra anyway using the Keck II telescope and its DEep Imaging Multi-Object Spectrograph and also Carnegie’s Magellan/IMACS instrumentation and were then able to measure the distance to Himiko.

Most of the extended Lyman-Alpha blobs discovered so far sit at distances when the Universe was two to three billion years old. But, the data show Himiko is located at the re-ionization epoch, which occurred between about 200 million and one billion years after the Big Bang and which is one of the earliest observable points in the history of the Universe. To better understand the re-ionization epoch, astronomers search for characteristic hydrogen signatures released when the region’s ionized gas clouds scatter light in a specific way. Theoretical studies suggest that the first stars and galaxies formed from neutral hydrogen atoms and that these objects subsequently emitted ultraviolet photons re-ionizing the Universe.

Himiko’s spectra clearly exhibited the re-ionization epoch characteristic hydrogen signature indicating that the object was actually at a distance of 12.9 billion light years, Ouchi says. The research appears in the May 10 issue of The Astrophysical Journal. 

Data taken with NASA’s infrared Spitzer Space Telescope, the United Kingdom Infrared Telescope, radio data from the Very Large Array and X-ray imaging from the XMM-Newton satellite allowed astronomers to estimate Himiko’s visible mass and its star formation rate. The astronomers have also begun investigating whether the object contains a central, active super-massive black hole at its core.

Himiko’s existence is puzzling, however, because if it marks a new class of objects that are ancestors of today’s galaxies, astronomers should have already found smaller ones in distant regions, says team member Alan Dressler also of Carnegie. But this object is currently one-of-a-kind. Its discovery therefore makes it hard to fit the object into the prevailing model of how normal galaxies were assembled.

The team’s research was funded by the NASA through an award issued by JPL/Caltech, the Department of Energy, and the Carnegie Institution. The result is based in part on data collected at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the Spitzer Telescope, managed by JPL for NASA; the Magellan telescopes operated by a consortium consisting of the Carnegie Institution, Harvard University, MIT, the University of Michigan, and the University of Arizona; and the United Kingdom Infrared Telescope, which is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the UK.

Cluster Heavyweights Caught in Cosmic Traffic Jam

Astronomers have recently identified the Universe’s most crowded cosmic free-way, where monster galaxy clusters are slamming together in one of the largest collisions ever recorded. Pinpointing such a pile-up required data from three of the world’s best telescopes, and the discovery now provides scientists with a chance to watch what happens when some of the Universe’s largest objects collide. 

A team of astronomers from the University of Hawai’i used the W. M. Keck Observatory on Mauna Kea, Hawai’i, and the space-based Chandra X-ray Observatory and Hubble Space Telescope, both NASA missions, to collect their data. The team then calculated the three-dimensional geometry and motion in the system MACSJ0717.5+3745, or MACSJ0717 for short, which is located about 5.4 billion light years from Earth in the direction of the Hydra constellation.

The researchers’ new data shows that four separate galaxy clusters are involved in a triple collision. Galaxy clusters are the largest objects bound by gravity in the Universe, and it is the first time astronomers have ever observed such a massive merger. Only by observing such violent collisions can astronomers better understand how clusters grow, says the team’s lead researcher Cheng-Jiun Ma of the University of Hawai’i.

To make such observations, the astronomers used the Keck II telescope and its DEIMOS instrument from 2004 to 2008, as well as the Hubble Space Telescope in 2004, as part of an ongoing research project to learn more about cluster and galaxy evolution.

Taking spectroscopic data is the only way to measure galaxy velocities along the line of sight. This data adds the crucial third dimension to what the team can learn about the dynamics of a large cluster from its gas and galaxy densities, says team member Harald Ebeling, also of the University of Hawai’i. The DEIMOS instrument’s large field of view and Keck’s massive light gathering power make the instrument and telescope the only research tool that can survey a structure as large as MACSJ0717 in a reasonable amount of time.

“After all, this cluster is at a few billions of light years from Earth, meaning it takes one to two hours even with Keck to measure reliable radial velocities for cluster galaxies,” Ebeling notes.

The optical data provides information about the radial motion and density of galaxies. The team then combined the Hubble and Keck data with information taken with the Chandra X-ray Observatory to determine the three-dimensional geometry and motion in the system and how that motion affects the collisions.

The data revealed a large, hot region located where a long stream of galaxies and gas—known as a filament—runs into MACSJ0717. The filament extends 13 million light years and pours gas and galaxies into the system like cars exiting a crowded interstate into a full parking lot. This influx of matter causes one collision after another.

Each of the collisions releases energy in the form of heat. MACSJ0717 therefore has one of the highest temperatures ever seen in such a system, Ma explains.

The filament leading into MACSJ0717 had been previously discovered. But the new results show that it is the source of the cluster collisions. The evidence is two-fold. First, by comparing the position of the gas and clusters of galaxies, the researchers tracked the direction of clusters’ motions, which matched the orientation of the filament in most cases. Second, the large hot region in MACSJ0717 is located where the filament intersects the cluster, suggesting ongoing impacts.

“MACSJ0717 shows how giant galaxy clusters interact with their environment on scales of many millions of light years,” Ebeling says. “This is a wonderful system for studying how clusters grow as material falls into them along the filaments.”

Computer simulations show that the most massive galaxy clusters should grow in regions where large-scale filaments of intergalactic gas, galaxies, and dark matter intersect, and material falls inward along the filaments.

“It’s exciting that the data we get from MACSJ0717 appear to beautifully match the scenario depicted in the simulations,” Ma adds.

In the future, he and his colleagues want to use even deeper X-ray data to measure the temperature of gas over the full 13 million light year extent of the filament to learn more about how structure in the Universe grows and evolves.

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass. NASA Goddard Space Flight Center in Greenbelt, MD performs the daily orbital operations, servicing mission development, and overall management of the Hubble Program. The Space Telescope Science Institute (STScI) in Baltimore, MD develops and executes Hubble’s scientific program and is managed by the Association of Universities for Research in Astronomy (AURA) under contract to NASA.

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 operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. For information please call 808.885.7887 or visit www.keckobservatory.org.

Keck and Kepler team up to find other Earths

Kamuela, Hawaii—  For nearly a decade, Cal-Berkeley astronomer Geoff Marcy and his colleagues have been using the W. M. Keck telescopes to discover giant planets orbiting distant stars. Now, with the successful launch of NASA’s Kepler mission, they will be using Keck I’s ten-meter astronomical eye to discover distant Earths. Kepler will pick out Earth-like candidates. Keck will then zero in on them and determine, with certainty, if they are at all similar to our home planet.

“Keck and NASA have a long-standing partnership to push astronomy research to its fullest potential. This Keck-Kepler collaboration gives that partnership a compelling new scientific focus,” said Taft Armandroff, the Director of Keck Observatory headquartered in Kamuela, HI.

Kepler was launched from NASA’s Kennedy Space Center last Friday.  Aboard the spacecraft is an 84-megapixel camera that will focus on a single region of the sky and snap repeated images of 100,000 stars looking for those that dim periodically. By studying the stars’ episodic decreases in starlight, astronomers will be able to determine the diameter of the object that passes in front of the star, blocks its light and causes the dimming.

“Kepler does not tell astronomers with certainty if the object taking a bite out of the starlight is a planet or another star. That is where Keck plays a crucial role to the Kepler mission,” said Marcy, a frequent Keck user and Kepler mission co-investigator. He, along with a large international planet-hunting team, has discovered nearly half of the 300-plus known planets outside the Solar System.

Astronomers call the objects Kepler detects transits because from the telescope’s perspective the planet candidate seems to eclipse its parent star’s light. The phenomenon is similar to the Moon eclipsing the Sun during a total solar eclipse. But a distant planet eclipsing its parent star will only block a small fraction, 1/10,000, of the star’s light. The Moon, by contrast, blocks nearly all of the Sun’s light in a total solar eclipse.

In the Kepler-Keck duo, once Kepler team members find an Earth candidate and determine as best they can that they’re not looking at two stars orbiting each other, they will hand the object off to Marcy and his colleagues. The team will use Keck I telescope and its instrument HIRES, the High Resolution Spectrometer, to monitor how the light coming from the parent star changes as the planet candidate orbits.

HIRES is an instrument that spreads light collected from the telescope mirrors into its component wavelengths or colors. This is called a spectrum. When the planet candidate orbits around the back of the star, its gravity will ever so slightly pull on the star causing the star’s spectrum to shift toward redder wavelengths. When the planet comes around in its orbit to cross the face of the star, it will pull the star in the other direction, and the star’s spectrum will shift toward bluer wavelengths. HIRES will detect these shifts and give astronomers the star’s radial velocity, or the speed at which the star moves toward or away from Earth. Based on this speed, Marcy and his team will be able to calculate the mass of planet candidate.

“Keck’s HIRES is the only game in town that can measure spectral shifts caused by an Earth-sized planet. No other telescope-spectrograph combination is powerful enough,” Marcy said. “That is why NASA is really heavily dependent on the Keck telescopes right now.”

Calculating the planet candidate’s mass is important because it tells astronomers whether a planet or another star is eclipsing the parent star. If the object turns out to be a planet, Marcy and his team can then use the Keck-calculated mass and Kepler-calculated diameter to determine the planet’s density. “In a sense it’s as if we are taking the planets and dunking them in a bathtub to see if they float. A rocky planet like Earth would sink,” Marcy said. Earth has a density of about five grams per cubic centimeter. Gas giants, on the other hand, have a density close to water at about one gram per cubic centimeter.

“Studying the radial velocity of the planet candidates Kepler discovers is a key endeavor in understanding our place in the cosmos. It will help answer one of humanity ’biggest questions, “Are we alone?” Armandroff said.

Marcy and his colleagues started studying Kepler’s candidate planets with Keck I and HIRES during the last three nights of July 2009.

Kepler is a NASA Discovery mission. NASA Ames Research Center, Moffett Field, Calif., is the home organization of the science principal investigator, and is responsible for the ground system development, mission operations and science data analysis. Jet Propulsion Laboratory, Pasadena, Calif., manages the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., is responsible for developing the Kepler flight system and supporting mission operations. For more information about the Kepler mission, visit: http://www.nasa.gov/kepler.

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.

Maunakea Lecture Series Celebrates the International Year of Astronomy 2009

Hawai‘i Island, HI –  The public is invited to attend The Maunakea 2009 Lecture Series, free monthly lectures throughout 2009 hosted by ‘Imiloa Astronomy Center and W. M. Keck Observatory to introduce Hawai’i astronomy and the latest research being done by the thirteen observatories located on the summit of Maunakea.  The Maunakea 2009 Lecture Series is the first of many activities planned locally to commemorate the International Year of Astronomy (IYA 2009), a global celebration of astronomy and its contributions to society and culture, with events happening worldwide in 135 countries.

The opening speaker in the 2009 Series is Chad Kalepa Baybayan, ‘Imiloa Astronomy Center’s Navigator-in-Residence, whose presentation will be Thursday, January 15 at the W. M. Keck Observatory’s Hualalai Learning Theater in Waimea and Saturday, January 17 at ‘Imiloa Astronomy Center’s planetarium in Hilo.  Both programs begin at 7 pm and space is limited to first-come, first served. 

Baybayan’s talk titled, “Traditional Hawaiian Navigation and Sky Lore,” will discuss how the earliest astronomers, the Hawaiians, used their powers of observation and knowing the movement of stars, as well as understanding of ocean and environmental conditions, for navigation and wayfinding.

Baybayan holds a masters degree in Education, is a fluent speaker of the Hawaiian language, and has served as captain and navigator aboard the Hawaiian deep-sea voyaging canoes Hōkūle‘a, Hawai’iloa, and Hōkūalaka’i. He has been an active participant in the Polynesian voyaging movement since 1975 and has sailed on all major voyages of the Hōkūle’a throughout Polynesia, Micronesia, the west coast of North America, and Japan. Currently he serves as the Navigator-in-Residence at the ‘Imiloa Astronomy Center of Hawai’i. He also serves as the resident captain and navigator aboard Hōkūalaka’i, the newest of a fleet of voyaging canoes that are symbolic of the growing interest among local Hawaiian communities in the voyaging arts. He is currently working to establish Hōkūalaka’i as a cornerstone voyaging program located in Keaukaha, a Hawaiian homestead community, on the island of Hawai‘i.

Following Baybayan’s talk, there will be presentations over the next eleven months by the directors of the Maunakea observatories who will share the latest scientific discoveries and technologies from their research facilities.  Over the last 400 years, telescopes and techniques have evolved to include instruments that “see” the heavens in many ways.  The telescopes on Maunakea each have unique capabilities, and many are world leaders in this legacy of exploration.

The programs in Hilo will take place in ‘Imiloa Astronomy Center’s 120-seat planetarium on the third Saturday of each month during 2009.  This special year-long program replaces the Center’s monthly “Maunakea Skies” planetarium talks, which will resume in 2010.  In addition to hearing the lecture, guests may also choose to dine before hand at ‘Imiloa’s Sky Garden Restaurant which will be open for dinner service from 5 pm to 8 pm.  For dinner reservations, call the restaurant directly at (808) 935-8888.

Opened in 2006, ‘Imiloa Astronomy Center celebrates both Hawaiian culture and Maunakea astronomy.  Through its exhibits and program, ‘Imiloa strives to share inspiring examples of science and culture together advancing knowledge, understanding and opportunity.  The Center is located at 600 ‘Imiloa Place in Hilo, off Komohana and Nowelo Streets at the UH-Hilo Science and Technology Park. For more information, go to http://www.imiloahawaii.org  or call (808) 969-9700 for recorded information, or (808) 969-9703.

The programs in Waimea take place at the W. M. Keck Observatory headquarters in the Hualalai Learning Theater at 65-1120 Mamalahoa Highway.  Keck Observatory operates twin 10-meter optical/infrared telescopes made possible by grants totaling more than $138 million from the W. M. Keck Foundation.  Keck I telescope began science observations in 1993, Keck II began in 1996.  The vision of the Keck Observatory is a world in which all humankind is inspired and united by the pursuit of knowledge of the infinite variety and richness of the Universe.  The W.M. Keck Observatory headquarters operates a small visitor/information center open to the public from 9:00 a.m. to 4:30 p.m. Monday through Friday.  For more information, visit http://www.keckobservatory.org  or call (808) 885-7887.

Discovery of Methane Reveals Mars Is Not a Dead Planet

WASHINGTON—A team of NASA and university scientists has achieved the first definitive detection of methane in the atmosphere of Mars. This discovery indicates the planet is either biologically or geologically active.

The team found methane in the Martian atmosphere by carefully observing the planet throughout several Mars years with NASA’s Infrared Telescope Facility and the W.M. Keck telescope, both at Mauna Kea, Hawaii. The team used spectrometers on the telescopes to spread the light into its component colors, as a prism separates white light into a rainbow. The team detected three spectral features called absorption lines that together are a definitive signature of methane.

“Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas,” said Michael Mumma of NASA’s Goddard Space Flight Center in Greenbelt, Md. “At northern mid-summer, methane is released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif.” Mumma is lead author of a paper describing this research that will appear in Science Express on Thursday.

Methane, four atoms of hydrogen bound to a carbon atom, is the main component of natural gas on Earth. Astrobiologists are interested in these data because organisms release much of Earth’s methane as they digest nutrients. However, other purely geological processes, like oxidation of iron, also release methane.

“Right now, we do not have enough information to tell whether biology or geology—or both—is producing the methane on Mars,” Mumma said. “But it does tell us the planet is still alive, at least in a geologic sense. It is as if Mars is challenging us, saying, ‘hey, find out what this means.’ ”

If microscopic Martian life is producing the methane, it likely resides far below the surface where it is warm enough for liquid water to exist. Liquid water is necessary for all known forms of life, as are energy sources and a supply of carbon.

“On Earth, microorganisms thrive about 1.2 to 1.9 miles beneath the Witwatersrand basin of South Africa, where natural radioactivity splits water molecules into molecular hydrogen and oxygen,” Mumma said. “The organisms use the hydrogen for energy. It might be possible for similar organisms to survive for billions of years below the permafrost layer on Mars, where water is liquid, radiation supplies energy, and carbon dioxide provides carbon. Gases, like methane, accumulated in such underground zones might be released into the atmosphere if pores or fissures open during the warm seasons, connecting the deep zones to the atmosphere at crater walls or canyons.”

It is possible a geologic process produced the Martian methane, either now or eons ago. On Earth, the conversion of iron oxide into the serpentine group of minerals creates methane, and on Mars this process could proceed using water, carbon dioxide and the planet’s internal heat. Although there is no evidence of active volcanism on Mars today, ancient methane trapped in ice cages called clathrates might be released now.

“We observed and mapped multiple plumes of methane on Mars, one of which released about 19,000 metric tons of methane,” said co-author Geronimo Villanueva of the Catholic University of America in Washington. “The plumes were emitted during the warmer seasons, spring and summer, perhaps because ice blocking cracks and fissures vaporized, allowing methane to seep into the Martian air.”

According to the team, the plumes were seen over areas that show evidence of ancient ground ice or flowing water. Plumes appeared over the Martian northern hemisphere regions such as east of Arabia Terra, the Nili Fossae region, and the south-east quadrant of Syrtis Major, an ancient volcano about 745 miles across.

One method to test whether life produced this methane is by measuring isotope ratios. Isotopes of an element have slightly different chemical properties, and life prefers to use the lighter isotopes. A chemical called deuterium is a heavier version of hydrogen. Methane and water released on Mars should show distinctive ratios for isotopes of hydrogen and carbon if life was responsible for methane production. It will take future missions, like NASA’s Mars Science Laboratory, to discover the origin of the Martian methane.

The research was funded by the Planetary Astronomy Program at NASA Headquarters in Washington and the Astrobiology Institute at NASA’s Ames Research Center in Moffett Field, Calif. The University of Hawaii manages NASA’s Infrared Telescope Facility.

For images related to this finding, visit:

http://www.nasa.gov/mars 

- end -

Astronomers use gamma-ray burst to probe star formation in the early universe

LONG BEACH, CA (January 6th, 2009) The brilliant afterglow of a powerful gamma-ray burst (GRB) has enabled astronomers to probe the star-forming environment of a distant galaxy, resulting in the first detection of molecular gas in a GRB host galaxy. By analyzing the spectrum of light emitted in the GRB afterglow, the researchers are gleaning insights into an active stellar nursery in a galaxy so far away it appears as it was 10 billion years ago.

“This observation required a rare and exceptionally bright event to allow us to probe the fragile environment where stars were forming just 3 billion years after the Big Bang. After correcting for the extreme dust extinction, this is intrinsically the second brightest GRB afterglow to date; it would have been easily observed with amateur telescopes, if not for the dust in the way,” said Jason X. Prochaska, professor of astronomy and astrophysics at the University of California, Santa Cruz.

Prochaska’s team will present its findings at the American Astronomical Society meeting this week in Long Beach, Calif. A paper describing the results has been accepted for publication in Astrophysical Journal Letters.

Stars form in vast clouds of molecular gas and dust, and astronomers have expected to find evidence of these molecular clouds in GRB host galaxies. Until now, however, efforts to detect molecular gas in GRB afterglow spectra had been unsuccessful. The new observations by Prochaska and his coauthors indicate that star formation in the early universe occurred in environments similar to star-forming regions in the Milky Way.

The study focused on a “long duration” gamma-ray burst known as GRB 080607. This type of burst is thought to occur when a massive star collapses to form a black hole. The initial burst of high-energy gamma rays was followed by a slowly fading afterglow of radiation over the entire spectrum of wavelengths.

“We suspect that previous events like 080607 were too faint to be observed on Earth,” said coauthor Yaron Sheffer of the University of Toledo. “Many so-called dark bursts, with no observable afterglow, probably mark the dusty, highly extinguished environments of young star-forming regions.”

NASA’s Swift satellite detected the gamma-ray burst and began x-ray observations, while alerting astronomers and triggering automatic observations by ground-based telescopes such as the Katzman Automatic Imaging Telescope at Lick Observatory. Team members Joshua Bloom, Daniel Perley, and Adam Miller of UC Berkeley happened to be using the Keck I Telescope at the W. M. Keck Observatory in Hawaii and began spectroscopic observations within 15 minutes using the Low Resolution Imaging Spectrograph (LRIS).

The resulting spectrum of the optical afterglow yielded information about the dust, gas, and metals in the interstellar medium through which the light passed on its way out of the host galaxy. In addition to the first clear detection of molecular gases (both carbon monoxide and hydrogen), the spectrum indicated a metal composition comparable to that of the Sun (to astronomers, “metals” are elements heavier than hydrogen and helium).

The spectrum also has many features researchers have never seen before, Prochaska said. In addition to hundreds of standard absorption lines corresponding to known transitions of various elements, the spectrum shows many absorption lines that researchers have yet to identify.

“This is easily the most fascinating spectrum that I’ve ever worked on,” Prochaska said. “Nearly half of the features remain a mystery, and it is possible that no one has ever detected them previously, either in controlled laboratory experiments or in spectra from our galaxy or other galaxies.”

There is also more hydrogen in this spectrum than along any path through the Milky Way, he added. “This remains a bit of a puzzle,” Prochaska said. “For now, we don’t know much about the galaxy that hosted the explosion, but the evidence suggests it has been prodigious in terms of star formation.”

The burst and its afterglow were observed in June, and the team did not manage to get images of the host galaxy before it moved to a position in the sky where it could not be observed. In January, the researchers will image the galaxy to connect their findings on the star-forming region with its global properties.

In addition to Prochaska, Sheffer, Perley, Miller, and Bloom, the coauthors include Laura Lopez of UC Santa Cruz; Miroslava Dessauges-Zavadsky of the Geneva Observatory, Switzerland; Hsiao-Wen Chen of the University of Chicago; and Alex Filippenko, Mo Ganeshalingam, Weidong Li, and Dan Starr of UC Berkeley.

This research was supported by the National Science Foundation, NASA, and the TABASGO Foundation.

ASTRONOMERS CAPTURE FIRST IMAGES OF NEWLY-DISCOVERED PLANETARY SYSTEM

Kamuela, HI (November 13th, 2008) Using high-contrast, near-infrared adaptive optics observations with the Keck and Gemini telescopes atop Mauna Kea, astronomers for the first time have taken snapshots of a multi-planet solar system, much like ours, orbiting another star.

The new solar system orbits the dusty young star named HR8799, which is 140 light years away and about 1.5 times the size of our sun. Three planets, roughly 10, 10 and 7 times the mass of Jupiter, orbit the star. The sizes of the planets decrease with distance from the parent star, much like the giant planets do in our system.

And there may be more planets out there that scientists just haven’t seen yet.
“Every extrasolar planet detected so far has been a wobble on a graph. These are the first pictures of an entire system,” said Bruce Macintosh, an astrophysicist from Lawrence Livermore National Laboratory and one of the key authors of a paper appearing in the Nov. 13 issue of Science Express. “We’ve been trying to image planets for eight years with no luck and now we have pictures of three planets at once.”

The team of researchers from Livermore, the NRC Herzberg Institute of Astrophysics in Canada, Lowell Observatory, UCLA, and several other institutions were able to see three orbiting planetary companions to HR 8799. The first author of the paper is Christian Marois, a former Livermore postdoctoral researcher who now works at NRC.

Astronomers have known for a decade through indirect techniques that the sun was not the only star with orbiting planets.

“But we finally have an actual image of an entire system,” Macintosh said. “This is a milestone in the search and characterization of planetary systems around stars.”

During the past 10 years, various planet detection techniques have been used to find more than 200 exoplanets. But these methods all have limitations. Most infer the existence of a planet through its influence on the star that it orbits, but don’t actually tell scientists anything about the planet other than its mass and orbit. Second, the techniques are all limited to small to moderate planet-star separation, usually less than about 5 AU. (Astronomical units; one AU is the average distance from the sun to Earth).

In the new findings, the planets are 24, 37 and 67 times the Earth-sun separation from the host star. The furthest planet in the new system orbits just inside a disk of dusty debris, similar to that produced by the comets of the Kuiper belt of our solar system (just beyond the orbit of Neptune at 30 times Earth-sun distance).

“HR 8799’s dust disk stands out as one of the most massive in orbit around any star within 300 light years of Earth,” said UCLA’S Ben Zuckerman.

In some ways, this planetary system seems to be a scaled-up version of our solar system orbiting a larger and brighter star.

The host star is a bright, blue A-type star, which has been mostly neglected in ground and space-based direct imaging survey since it offers a less favorable contrast between the bright star and faint planet. But they do have an advantage over our sun: early in their life, they can retain heavy disks of planet-making material and therefore form more massive planets at wider separations that are easier to detect. This star is also young - less than 100 million years old - which means its planets are still glowing with heat from their formation.

“Seeing these planets directly - separating their light from the star - lets us study them as individuals, and use spectroscopy to study their properties, like temperature or composition,” Macintosh said.

“Detailed comparison with theoretical model atmospheres confirms that all three planets possess complex atmospheres with dusty clouds partially trapping and re-radiating the escaping heat,” said Lowell Observatory astronomer Travis Barman.

The planets have been extensively studied using adaptive optics on the giant Keck and Gemini telescopes in Hawaii. Adaptive optics enables astronomers to minimize the blurring effects of the Earth’s atmosphere, producing images with unprecedented detail and resolution. LLNL helped build the original adaptive optics system for Keck, the world’s largest optical telescope. Marois developed an advanced computer processing technique that helps to extract the planets from the vastly brighter light of the star.

Keck Observatory Director Taft Armandroff is pleased with this new discovery enabled by adaptive optics. “In 1999, the Keck II telescope became the first large telescope worldwide to develop and install an adaptive optics system. The results have been dramatic. Keck’s adaptive optics systems routinely produce images with significantly greater clarity and detail than those resulting from Hubble Space Telescope. Keck is developing a next generation system that will produce images that are nearly perfectly corrected for atmospheric turbulence at infrared wavelengths, plus it will enable adaptive optics correction at optical wavelengths for the first time and increase the current very narrow fields of view that limit current adaptive optics systems,” Armandroff reported.

“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.”

The W. M. Keck Observatory (http://www.keckobservatory.org) is operated by the California Association for Research in Astronomy (CARA), a non-profit 501 (c) (3) corporation whose governing board consists of directors from the California Institute of Technology and the University of California. The twin ten-meter telescopes were made possible by grants totaling $138 million from the W. M. Keck Foundation; the Keck I telescope began science observations in 1993, Keck II began in 1996.

Keck Telescope and Cosmic Lens Resolve Nature and Fate of Early Star-Forming

PASADENA, Calif. (October 15th, 2008) Astronomers at the California Institute of Technology (Caltech) and their colleagues have provided unique insight into the nature of a young star-forming galaxy as it appeared only two billion years after the Big Bang and determined how the galaxy may eventually evolve to become a system like our own Milky Way.

The team made their observations by coupling two techniques, gravitational lensing—which makes use of an effect first predicted by Albert Einstein in which the gravitational field of massive objects, such as foreground galaxies, bends light rays from objects located a distance behind, thus magnifying the appearance of distant sources—and laser-assisted guide star (LGS) adaptive optics (AO) on the 10-meter Keck Telescope in Hawaii. Adaptive optics corrects the blurring effects of Earth’s atmosphere by real-time monitoring of the signal from a natural guide star or an artificial guide star. Gravitational lensing enlarged the distant galaxy in angular size by a factor of about 8 in each direction. Together with the enhanced resolution using adaptive optics, this allowed the team to determine the internal velocity structure of the remote galaxy, located 11 billion light-years from Earth, and hence its likely future evolution.

The researchers found that the distant galaxy, which is typical in many respects to others at that epoch, shows clear signs of orderly rotation. The finding, in association with observations conducted at millimeter wavelengths, which are sensitive to cold molecular gas (an indicator of galactic rotation), suggests that the source is in the early stages of assembling a spiral disk with a central nucleus similar to those seen in spiral galaxies at the present day.

Using the Hubble Space Telescope, the team located a distinctive galaxy dubbed the “Cosmic Eye” because its form is distorted into a ring-shaped structure by the gravitational field of a foreground galaxy.

“Gravity has effectively provided us with an additional zoom lens, enabling us to study this distant galaxy on scales approaching only a few hundred light-years. This is 10 times finer sampling than hitherto possible,” explains postdoctoral research scholar Dan Stark of Caltech, the leader of the study. “As a result, we can see, for the first time, that a typical-sized young galaxy is spinning and slowly evolving into a spiral galaxy much like our own Milky Way,” he says.

The research, described in the October 9 issue of the journal Nature, provides a demonstration of the likely power of the future Thirty Meter Telescope (TMT), the first of a new generation of large telescopes designed to exploit AO.

When completed in the latter half of the next decade, TMT’s large aperture and improved optics will produce images with an angular resolution three times better than the 10-meter Keck and 12 times better than the Hubble Space Telescope, at similar wavelengths. Because of the significant improvement in angular resolution provided by AO, the TMT will be able to study the internal properties of small distant galaxies, seen as they were when the universe was young.

Likewise, the Atacama Large Millimeter Array (ALMA), a large interferometer being completed in Chile, will provide a major step forward in mapping the extremely faint emission from cold hydrogen gas—the principal component of young, distant galaxies and a clear marker of cold molecular gas—compared to the coarser capabilities of present facilities. In their recent research, the Caltech-led team has provided a glimpse of what can be done with the superior performance expected of TMT and ALMA.

The key spectroscopic observations were made with the OSIRIS instrument, developed specifically for the Keck AO system by astrophysicist James Larkin and collaborators at the University of California, Los Angeles. Stark and his coworkers used the OSIRIS instrument to map the velocity across the source in fine detail, allowing them to demonstrate that it has a primitive rotating disk.

To aid in their analysis, the researchers combined data from the Keck Observatory with data taken at millimeter wavelengths by the Plateau de Bure Interferometer (PdBI), located in the French Alps. This PdBI instrument is sensitive to the distribution of cold gas that has yet to collapse to form stars. These observations give a hint of what will soon be routine with the ALMA interferometer.

“Remarkably, the cold gas traced by our millimeter observations shares the rotation shown by the young stars seen in the Keck observations. The distribution of gas seen with our amazing resolution indicates we are witnessing the gradual buildup of a spiral disk with a central nuclear component,” explains coinvestigator Mark Swinbank of Durham University, who was involved in both the Keck and PdBI observations.

This work demonstrates how important angular resolution has become in ensuring progress in extragalactic astronomy. This will be the key gain of both the TMT and ALMA facilities.

“For decades, astronomers were content to build bigger telescopes, arguing that light-gathering power was the primary measure of a telescope’s ability,” explains Richard S. Ellis, Steele Family Professor of Astronomy at Caltech, a coauthor on the Nature study, and a member of the TMT board of directors. “However, adaptive optics and interferometry are now providing ground-based astronomers with the additional gain of angular resolution. The combination of a large aperture and exquisite resolution is very effective for studying the internal properties of distant and faint sources seen as they were when the universe was young. This is the exciting future we can expect with TMT and ALMA, and, thanks to the magnification of a gravitational lens, we have an early demonstration here in this study,” he says.

Coauthors on the paper, “The formation and assembly of a typical star-forming galaxies at redshift z~3,” are Simon Dye of Cardiff University in Cardiff, Wales; Ian R. Smail of Durham University in Durham, England; and Johan Richard of Caltech.

The W. M. Keck Observatory operates twin 10-meter telescopes located on the summit of Mauna Kea. The observatory, made possible by grants from the W. M. Keck Foundation totaling over $138 million, is managed as a nonprofit corporation whose board of directors includes representatives from Caltech and the University of California.

The Thirty Meter Telescope is currently in a detailed design and development phase and represents a collaboration between Caltech, the University of California, and the Association for Canadian Universities Research in Astronomy. It has received generous support from the Gordon and Betty Moore Foundation.

Further information on the Thirty Meter Telescope is available at http://www.tmt.org. and: http://www.tmt.org/news/cosmic-lens.htm

Information on the Atacama Large Millimeter Array is available at http://www.alma.nrao.edu.

Further information on the Keck telescopes, their adaptive optics systems, and the OSIRIS instrument are available at: https://www.keckobservatory.org/.

KECK OBSERVATORY OPEN HOUSE SUNDAY, OCTOBER 12, 2008: WELCOME TO THE EDGE OF DISCOVERY

(September 4th, 2008) W. M. Keck Observatorys 2008 Open House will feature “hands-on activities” and displays presenting the science, technology and excitement of astronomy.

MOST BLACK HOLES MIGHT COME IN ONLY SMALL AND LARGE

(August 20th, 2008) Black holes are sometimes huge cosmic beasts, billions of times the mass of our sun, and sometimes petite with just a few times the sun’s mass. But do black holes also come in size medium? Research combining data from the European Space Agency’s XMM-Newton space telescope and the W. M. Keck Observatory suggests that, for the most part, the answer is no.

Astronomers have long suspected that the most likely place to find a medium-mass black hole would be at the core of a miniature galaxy-like object called a globular cluster. Yet, nobody has been able to find one conclusively.

Now, a team of astronomers has thoroughly examined a globular cluster called RZ2109 and determined that it cannot possess a medium black hole. The findings suggest that the elusive objects do not lurk in globular clusters, and perhaps are very rare.

“Some theories say that small black holes in globular clusters should sink down to the center and form a medium-sized one, but our discovery suggests this isn’t true,” said Daniel Stern of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Stern is second author of a study detailing the findings in the Aug. 20 issue of Astrophysical Journal. The lead author is Stephen Zepf of Michigan State University, East Lansing.

Black holes are incredibly dense points of matter, whose gravity prevents even light from escaping. The least massive black holes known are about 10 times the mass of the sun and form when massive stars blow up in supernova explosions. The heftiest black holes are up to billions of times the mass of the sun and lie deep in the bellies of almost all galaxies.

That leaves black holes of intermediate mass, which were thought to be buried at the cores of globular clusters. Globular clusters are dense collections of millions of stars, which reside within galaxies containing hundreds of billions of stars. Theorists argue that a globular cluster should have a scaled down version of a galactic black hole. Such objects would be about 1,000 to 10,000 times the mass of the sun, or medium in size on the universal scale of black holes.

In a previous study, Zepf and his colleagues looked for evidence of a black hole in RZ2109, located 50 million light-years away in a nearby galaxy. Using ESA’s XMM-Newton telescope (which derives its name from X-ray Multi-Mirror design), they discovered the telltale X-ray signature of an active, or “feeding” black hole. But, at that point, they still didn’t know its size.

Zepf and Stern then teamed up with others to obtain a chemical fingerprint, called a spectrum, of the globular cluster, using the W.M. Keck Observatory on Mauna Kea in Hawaii. The spectrum revealed that the black hole is petite, with roughly 10 times the mass of our sun.

According to theory, a cluster with a small black hole cannot have a medium one too. Medium black holes would be quite hefty with a lot of gravity, so if one did exist in a globular cluster, scientists argue that it would quickly drag any small black holes into its grasp.

“If a medium black hole existed in a cluster, it would either swallow little black holes or kick them out of the cluster,” said Stern. In other words, the small black hole in RZ2109 rules out the possibility of a medium one.

How did the scientists figure out that the globular cluster’s black hole was small in the first place? Using modeling techniques, Zepf and his colleagues concluded that the spectrum taken by Keck reveals high-velocity flows of matter, or “winds,” firing out of the black hole. Only a small black hole could spit out these observed high winds.

Zepf explains, “We knew from X-ray data that this black hole was actively swallowing up, or accreting, material. If an intermediate-sized black hole were accreting this material, it wouldn’t be too big of a deal for it. But if a small black hole were accreting this material, it would be a lot for it to take and therefore some material would be ejected in the form of high winds. Thus, the high winds were our smoking gun showing that this black hole is small.”

Is this the end of the story for medium black holes? Zepf said that it is possible such objects are hiding in the outskirts of galaxies like our Milky Way, either in surrounding so-called dwarf galaxies or in the remnants of dwarf galaxies being swallowed by a bigger galaxy. If so, the black holes would be faint and difficult to find.

Other authors of this paper include: Thomas Maccarone of the University of Southampton, England; Arunav Kundu of Michigan State University; Marc Kamionkowski of the California Institute of Technology, Pasadena; Katherine Rhode and John Salzer of the Indiana University, Bloomington; and Robin Ciardullo and Caryl Gronwall of Penn State University, University Park, Pa. Salzer is also with the Wesleyan University, Middleton, Conn.

For more information, visit:
W. M. Keck Observatory
European Space Agency XMM Newton telescope
Jet Propulsion LaboratoryJet Propulsion Laboratory

RARE STAR MAKING MACHINE FOUND IN EARLY UNIVERSE

(July 11th, 2008) Astronomers have uncovered an extreme stellar machine of a galaxy in the very remote universe, pumping out stars at a surprising rate of up to 4,000 per year. In comparison, our own Milky Way galaxy turns out an average of just 10 stars per year. The discovery was made possible by combining data from several telescopes atop Mauna Kea and NASA’s Hubble and Spitzer Space Telescopes. The Keck II telescope together with the DEep Imaging Multi-Object Spectrograph (DEIMOS) were used to discover the galaxy lies in the distant universe. The extreme distance of 12.3 billion light years places it in the universe’s infancy.

“This galaxy is undergoing a major baby boom, producing most of its stars all at once,” said Peter Capak of NASA’s Spitzer Science Center at the California Institute of Technology, Pasadena. “If our human population was produced in a similar boom, then almost all of the people alive today would be the same age.” Capak is lead author of a new report detailing the discovery in the July 10th issue of Astrophysical Journal Letters.

The results go against the most common theory of galaxy formation. According to the theory, called the Hierarchical Model, galaxies slowly bulk up their stars over time by absorbing tiny pieces of galaxies—and not in one big burst as observed in the newfound “Baby Boom” galaxy.

The Baby Boom galaxy, which belongs to a class of galaxies called starbursts, is the new record holder for the brightest starburst galaxy in the very distant universe, with brightness being a measure of its extreme star-formation rate. It was discovered and characterized using a suite of telescopes operating at different wavelengths. NASA’s Hubble Space Telescope and Japan’s Subaru Telescope, atop Mauna Kea in Hawaii, first spotted the galaxy in visible-light images, where it appeared as an inconspicuous smudge due to is great distance.

It wasn’t until Spitzer and the James Clerk Maxwell Telescope, also on Mauna Kea in Hawaii, observed the galaxy at infrared and submillimeter wavelengths, respectively, that the galaxy stood out as the brightest of the bunch. This is because it has a huge number of youthful stars. When stars are born, they shine with a lot of ultraviolet light and produce a lot of dust. The dust absorbs the ultraviolet light but, like a car sitting in the sun, it warms up and re-emits light at infrared and submillimeter wavelengths, making the galaxy unusually bright to Spitzer and the James Clerk Maxwell Telescope.

To learn more about this galaxy’s unique youthful glow, Capak and his team followed up with a number of telescopes. They used optical measurements from Keck to determine the exact distance to the galaxy—a whopping12.3 billion light-years. That’s looking back to a time when the universe was 1.3 billion years old (the universe is approximately 13.7 billion years old today).

“If the universe was a human reaching retirement age, it would have been about 6 years old at the time we are seeing this galaxy,” said Capak.

The astronomers made measurements at radio wavelengths with the National Science Foundation’s Very Large Array in New Mexico. Together with Spitzer and James Clerk Maxwell data, these observations allowed the astronomers to calculate a star-forming rate of about 1,000 to 4,000 stars per year. At that rate, the galaxy needs only 50 million years, not very long on cosmic timescales, to grow into a galaxy equivalent to the most massive ones we see today.

While galaxies in our nearby universe can produce stars at similarly high rates, the farthest one known before now was about 11.7 billion light-years away, or a time when the universe was 1.9 billion years old.

“Before now, we had only seen galaxies form stars like this in the teenaged universe, but this galaxy is forming when the universe was only a child,” said Capak. “The question now is whether the majority of the very most massive galaxies form very early in the universe like the Baby Boom galaxy, or whether this is an exceptional case. Answering this question will help us determine to what degree the Hierarchical Model of galaxy formation still holds true.”

“The incredible star-formation activity we have observed suggests that we may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe,” said Nick Scoville, the principal investigator of the Cosmic Evolution Survey, also known as Cosmos, and a co-author of the study. The Cosmos program is an extensive survey of a large patch of distant galaxies across the full spectrum of light.

“The immediate identification of this galaxy with its extraordinary properties would not have been possible without the full range of observations in this survey,” said Scoville.

The W. M. Keck Observatory operates twin 10-meter telescopes located on the summit of Mauna Kea. Made possible by grants from the W. M. Keck Foundation totaling over $138 million, the Observatory is managed as a non-profit corporation whose board of directors includes representatives from the California Institute of Technology and the University of California. For more information, visit http://www.keckobservatory.org

ASTRONOMERS WEIGH THE COLDEST BROWN DWARFS WITH ASTRONOMY’S SHARPEST EYES

Honolulu (June 2nd, 2008) Astronomers have used ultrasharp images obtained with the Keck Telescope and Hubble Space Telescope to determine for the first time the masses of the coldest class of “failed stars,” a.k.a. brown dwarfs. With masses as light as 3 percent the mass of the sun, these are the lowest mass free-floating objects ever weighed outside the solar system. The observations are a major step in testing the theoretical predictions of objects that cannot generate their own internal energy, both brown dwarfs and gas-giant planets. The new findings, which are being presented in a press conference today at the American Astronomical Society meeting in St. Louis, show that the predictions may have some problems.

“Mass is the fundamental parameter that governs the life-history of a free-floating object, and thus after many years of patient measurements, we are delighted to report the first masses of the very faintest, coldest brown dwarfs,” said Dr. Michael Liu of the Institute for Astronomy at the University of Hawaii (IfA/UH). “After weighing these tiny, dim, cold objects, we have confirmed that the theoretical predictions are mostly correct, but not entirely so.” The team announcing the results is composed of Dr. Liu, Mr. Trent J. Dupuy (IfA/UH), and Dr. Michael J. Ireland (University of Sydney).

Brown dwarfs are a class of objects that represent the missing link between the lowest-mass stars and the gas-giant planets, such as Jupiter and Saturn. Brown dwarfs are the faintest and coolest objects that can be directly observed outside the solar system. They emit as little as about 1/300,000 the energy of the sun and have surface temperatures comparable to the inside of a pizza oven (800° F), more than 9,000° F cooler than the surface of the sun.

“Astronomers have measured the energy output and temperatures for a myriad of brown dwarfs. However, the most important property of all is the hardest one to measure—the mass,” said Dr. Ireland.

To determine the masses, the team has spent the last several years studying brown dwarfs that occur in binaries, that is two brown dwarfs that are mutually bound together by gravity and orbit each other, in a fashion similar to how Earth orbits the sun. As first shown by Johannes Kepler in the 17th century, the total mass of any binary system can be determined by precisely measuring the orbit’s size and how long it takes for the two objects to complete one orbital cycle.

“These are very challenging measurements, because brown dwarf binaries have tiny separations on the sky and orbit each other very slowly. We needed to obtain the sharpest measurements that are possible with current telescopes to precisely monitor their motion,” said Mr. Dupuy.

The astronomers obtained images using the 10-meter (400-inch) Keck II Telescope on Mauna Kea, Hawaii. Keck II is equipped with a powerful adaptive optics system that corrects for the blurring of astronomical images caused by turbulence in Earth’s atmosphere. The Keck system can also employ a low-power laser to create an “artificial” star to enable such correction for almost anywhere in the sky.

The resulting images have an angular resolution as good as 1/20 of an arc second, about 1/40,000 the diameter of the full moon. A person with vision as sharp as the Keck adaptive optics system would be able to read a magazine that was about a mile away. In fact, the positional accuracy achieved with such sharp images is equivalent to hitting a bull’s-eye on a dartboard that is 8,000 miles away.

By regularly monitoring binaries with Keck adaptive optics and analyzing previous data obtained by the Hubble Space Telescope, the team was able to precisely measure the size and duration of the binaries’ orbits, and thereby determine the masses.

The team measured the masses of two brown dwarf binaries. One, known as 2MASS 1534-2952AB, is composed of two “methane” brown dwarfs, the coolest type of brown dwarf, which is characterized by the presence of methane gas in their atmospheres. This is the first mass measurement for this type of brown dwarf. The team found that the total mass of 2MASS 1534-2952AB is only 6 percent of the sun’s mass, and each brown dwarf in it has a mass of about 3 percent of the sun’s (about 30 times the mass of Jupiter). The other binary system, HD 130948BC, is a pair of slightly warmer “dusty” brown dwarfs with a total mass of only 11 percent of the sun’s mass and individual masses of about 5.5 percent of the sun’s.

Theoretical models predict the masses of brown dwarfs based on their energy output and temperature. But when the team compared their mass measurements to the theoretical predictions, they did not agree. For example, the surface temperature of 2MASS 1534-2952AB was much cooler than expected given its current level of energy output, while HD 130948BC was much warmer.

“While there is general agreement between our data and the predictions, something is not quite right with the theoretical studies of brown dwarfs, either in determining their temperatures or in predicting their energy output. Or perhaps both,” said Dr. Liu. “These findings will be a challenge for the theorists, and we are inspired to measure the masses of more brown dwarfs in the coming years to better understand the problem.”

The two binaries, located in the constellations of Libra (the Scales) and Bootes (the Herdsman), are about 45-60 light-years from Earth. The two components of each binary have a typical separation of about 2 astronomical units (AU), where 1 AU is the distance from Earth to the sun (93 million miles). This is somewhat larger than the 1.5 AU distance between Mars and the sun. Their orbital periods are about 10-15 years, compared with 2 years for Mars around the sun.

The team’s results are described in two upcoming papers submitted to the Astrophysical Journal. This research has been supported by the National Science Foundation and the Alfred P. Sloan Foundation.

First discovered in 1995, brown dwarfs represent a class of objects with masses less than 7 percent the mass of the sun (about 70 times Jupiter’s mass). While ordinary stars become hot and dense enough in their interiors to generate their own energy via nuclear fusion, brown dwarfs have insufficient mass to do this, so instead they steadily fade and cool over their lifetime. In many ways, brown dwarfs are very similar to gas-giant planets like Jupiter and Saturn, since both types of objects are unable to steadily generate their own energy and have very low surface temperatures.

FIGURE CAPTIONS

Figure 1. Infrared image of the very low-temperature binary 2MASS 1534-2952AB, composed of two methane brown dwarfs. This was obtained with the laser guide star adaptive optics system on the Keck II Telescope, located on Mauna Kea, Hawaii. The image is 1.5 arc seconds across (about 1/1,000 of the size of the moon), and the binary’s separation is about 0.2 arc seconds. Each component of the binary has a mass of about 3 percent the mass of the sun and emits about 1/100,000 the energy of the sun. These are the coolest free-floating objects ever directly weighed outside the solar system. Credit: Dr. Michael Liu (Institute for Astronomy, University of Hawaii).

Figure 2. Infrared image of the dusty brown dwarf binary HD 130948BC. The binary is seen in the upper left and has a total mass about 11 percent the mass of the sun. The binary is in orbit around a young sun-like star, seen to the lower right. This image was obtained with the adaptive optics system on the Keck II Telescope, located on Mauna Kea, Hawaii. The image is 3.75 arc seconds on a side (about 1/500 the size of the moon), and the binary’s separation is about 0.1 arc seconds. Credit: Mr. Trent Dupuy and Dr. Michael Liu (Institute for Astronomy, University of Hawaii).

Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea.

Established in 1907 and fully accredited by the Western Association of Schools and Colleges, the University of Hawaii is the state’s sole public system of higher education. The UH System provides an array of undergraduate, graduate, and professional degrees and community programs on 10 campuses and through educational, training, and research centers across the state. UH enrolls more than 50,000 students from Hawaii, the U.S. mainland, and around the world.

The W. M. Keck Observatory operates twin 10-meter telescopes located on the summit of Mauna Kea on the island of Hawaii and is managed by the California Association for Research in Astronomy, a non-profit corporation whose board of directors includes representatives from Caltech and the University of California. For more information, please visit: http://www.keckobservatory.org.

The Hubble Space Telescope is operated by the Space Telescope Science Institute with funding from NASA.

KECK, HUBBLE IMAGES SHOW CONTINUED TURBULENCE IN JUPITER’S ATMOSPHERE

Berkeley (May 22nd, 2008) Increased turbulence and storms first observed on Jupiter more than two years ago are still raging, according to astronomers from the University of California, Berkeley, and the W. M. Keck Observatory in Hawaii, who snapped high-resolution pictures of the planet earlier this month.

Captured with NASA’s Hubble Space Telescope (HST) and the 10-meter Keck II telescope, this so-called “major upheaval” on Jupiter involves stunning changes in the planet’s atmosphere, said lead astronomer Imke de Pater, professor of astronomy at UC Berkeley.

The images are available on NASA’s Web site, NASA’s HubbleSite NewsCenter

The upheaval was heralded in December 2005 by a color change from white to red of a large oval near the Great Red Spot, earning it the moniker Red Spot Jr. This oval, formally known as Oval BA, formed six years earlier through a merger of three large white ovals just south of the Great Red Spot – storms that formed in the early 1930s and were prominent in the Voyager era.

The new images, the first since Jupiter emerged from its passage behind the Sun, may show that Jupiter indeed is undergoing a major climate change, as predicted four years ago.

“One of the most notable changes we observe in both the Hubble and Keck images is the change from a rather bland, quiescent band surrounding the Great Red Spot just over a year ago to one that is incredibly turbulent at both sides of the spot,” de Pater said. “During all previous HST observations and spacecraft encounters, starting with Voyager in 1979, such turbulence was seen only on the west or left side of the spot.”

The Great Red Spot is a persistent, high-pressure storm on Jupiter whose cloud head sticks some 8 kilometers (5 miles) above the surrounding cloud deck. Why the spots are red is a subject of great debate.

Moreover, the color of several bands on the planet has been changing since the upheaval began, said Christopher Go, an amateur astronomer in Cebu, the Philippines, who joined de Pater’s team two years ago. Go alerted the astronomical community in early 2006 about the color change of Red Spot Jr.

“Lately, the red color of the Oval BA has faded a little bit, while the Great Red Spot may have turned dark red,” Go said.

The UC Berkeley team will work with the amateur astronomy community to investigate the possible origin of this turbulence, which is not understood.

The Great Red Spot and Red Spot Jr. are squeezed between bands called shear flows, where the flow above each storm is moving westward and the flow below is moving eastward. Since the shear flow in each band is slightly different, and the storms are different sizes, Red Spot Jr. drifts slowly eastward toward the Great Red Spot while the Great Red Spot drifts slightly westward toward Red Spot Jr. In late June, this storm will pass the Great Red Spot, as it does every two years.

Interestingly, a third red spot has appeared to the west of the Great Red Spot in the same latitude band.

“Although much smaller in extent, the color is striking,” said UC Berkeley team member Michael Wong. ““Like the other two large red storm systems, this newest red spot is bright in near-infrared wavelengths and dark in the ultraviolet. If this spot and the Great Red Spot continue on their courses, they will encounter each other in August, and the small oval will either be absorbed or repelled from the Great Red Spot.”

According to Philip S. Marcus, a professor of fluid dynamics at UC Berkeley, analysis of the Hubble and Keck images may support his 2004 conjecture that Jupiter is in the midst of global climate change that will alter temperatures by as much as 10 degrees Celsius, getting warmer near the equator and cooler near the south pole. He predicted that large changes would start in the southern hemisphere around 2006, causing the jet streams to become unstable and spawn new vortices.

“The appearance of the planet’s cloud system from just north of the equator down to 34 degrees south latitude keeps surprising us with changes and, in particular, with new cloud features that haven’t been previously observed,” Marcus said. “Whether or not Jupiter’s climate has changed due to a predicted warming, the cloud activity over the last two and a half years shows dramatically that something unusual has happened.”

“A major goal in taking the Hubble images is to look for changes in the zonal wind profile since the Cassini encounter in 2000,” added team member Xylar Asay-Davis. “If we do find major changes, these could provide important supporting evidence for climate change on Jupiter.”

The red coloration in the ovals may be generated as their swirling hazes rise to heights like the clouds of the Great Red Spot. Detailed analysis of the Hubble’s visible light data and the Keck images at near-infrared wavelengths will reveal the relative altitudes of the cloud tops of the three red ovals, de Pater said. Since all three oval storms are bright at near-infrared wavelengths where methane gas is absorbing, the data already show that all three systems rise up well above the surrounding cloud deck.

The Hubble telescope imaged the entire planet on May 9 and 10 using the Wide-Field Planetary Camera 2, while Keck II focused on the area around the Great Red Spot on May 11 using adaptive optics to sharpen the image.

Dr. Al Conrad, a support astronomer at the Keck Observatory, noted that the team used adaptive optics (AO) to obtain a spatial resolution comparable to that obtained at visible wavelengths with the Hubble telescope. Adaptive optics can take the twinkle out of an object caused by turbulence in the atmosphere, but to do this well, the target must be near another bright object that can serve as a reference. For some of the images, Jupiter’s moon Europa was used as the reference “star.” But until Europa was visible off the limb of Jupiter, a laser guide star was created near Jupiter to serve this purpose.

“This was our second attempt using the laser to obtain AO-corrected images of Jupiter’s surface,” Conrad said. “Based on our past experience, we placed the laser beacon slightly farther from Jupiter’s bright glow. With this adjustment in place, AO revealed much finer detail on the surface than we saw during our previous observation. By using the laser whenever there is no moon available as an AO reference, we will now have many more opportunities to observe Jupiter with Keck.”

In addition to images at 1.2-1.65 microns, where Jupiter’s reflected infrared light is measured, the team also obtained a close-up of the three spots at the somewhat longer infrared wavelength of 5 microns that samples thermal radiation from deeper in the atmosphere. All three spots appear dark on the 5-micron image because the clouds obscure heat emanating from lower elevations.

‘‘This image is spectacular,’’ says de Pater. “There is an amazing amount of fine structure and numerous small ovals south of the spots. This image reveals details in the cloud opacity not seen at the other wavelengths.”

The W. M. Keck Observatory operates twin 10-meter telescopes located on the summit of Mauna Kea on the island of Hawaii and is managed by the California Association for Research in Astronomy, a non-profit corporation whose board of directors includes representatives from Caltech, the University of California and NASA. For more information, please visit: http://www.keckobservatory.org.

The Hubble Space Telescope is operated by the Space Telescope Science Institute with funding from NASA.

The Hubble team consisted of de Pater, Marcus, Wong and Asay-Davis of UC Berkeley and Go of the Philippines. The Keck team members were de Pater, Wong and Conor Laver of UC Berkeley and Conrad of the Keck Observatory. The contributions by the amateur network http://jupos.privat.t-online.de/ was invaluable for this research.

NOTE: Imke de Pater; Michael Wong, Phil Marcus and Al Conrad can be reached at .(JavaScript must be enabled to view this email address), .(JavaScript must be enabled to view this email address), .(JavaScript must be enabled to view this email address) and .(JavaScript must be enabled to view this email address), respectively.

For more information on Jupiter’s recent turbulence, link to Christopher Go’s Web site: http://jupiter.cstoneind.com.

COMPACT GALAXIES IN EARLY UNIVERSE PACK A BIG PUNCH

Baltimore, Md. (April 29th, 2008) Imagine receiving an announcement touting the birth of a baby 20 inches long and weighing 180 pounds. After reading this puzzling message, you would immediately think the baby’s weight was a misprint.

Astronomers using NASA’s Hubble Space Telescope and the W. M. Keck Observatory on Mauna Kea, Hawaii, received a similar perplexing announcement when they found nine young, compact galaxies, each weighing in at 200 billion times the mass of the Sun. The galaxies, each only 5,000 light-years across, existed 11 billion years ago, when the universe was less than 3 billion years old. They are a fraction of the size of today’s grownup galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.

“Seeing the compact sizes of these galaxies is a puzzle,” said Pieter G. van Dokkum of Yale University in New Haven, Conn., who led the study. “No massive galaxy at this distance has ever been observed to be so compact. It is not yet clear how they would build themselves up to become the large galaxies we see today. They would have to change a lot over 11 billion years, growing five times bigger. They could get larger by colliding with other galaxies, but such collisions may not be the complete answer.”

To determine the sizes of the galaxies, the team used the Near Infrared Camera and Multi-Object Spectrometer on Hubble. The Keck observations were carried out with assistance of a powerful laser to correct for image blurring caused by the Earth’s atmosphere. “Only Hubble and Keck can see the sizes of these galaxies because they are very small and far away,” van Dokkum explained.

Van Dokkum and his colleagues studied the galaxies in 2006 with the Gemini South Telescope Near-Infrared Spectrograph, on Cerro Pachon in the Chilean Andes. Those observations provided the galaxies’ distances and showed that the stars are a half a billion to a billion years old. The most massive stars had already exploded as supernovae.

“In the Hubble Deep Field, astronomers found that star-forming galaxies are small,” said Marijn Franx of Leiden University, The Netherlands. “However, these galaxies were also very low in mass. They weigh much less than our Milky Way. Our study, which surveyed a much larger area than in the Hubble Deep Field, surprisingly shows that galaxies with the same weight as our Milky Way were also very small in the past. All galaxies look really different in early times, even massive ones that formed their stars early.”

The ultradense galaxies might comprise half of all galaxies of that mass 11 billion years ago, van Dokkum said, forming the building blocks of today’s largest galaxies.

How did these small, crowded galaxies form? One way, suggested van Dokkum, involves the interaction of dark matter and hydrogen gas in the nascent universe. Dark matter is an invisible form of matter that accounts for most of the universe’s mass. Shortly after the Big Bang, the universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in puddles of the invisible material and began spinning rapidly in dark matter’s gravitational whirlpool, forming stars at a furious rate.

Based on the galaxies’ masses, which are derived from their color, the astronomers estimated that the stars are spinning around their galactic disks at roughly 890,000 to 1 million miles an hour (400 to 500 kilometers a second). Stars in today’s galaxies, by contrast, are traveling at about half that speed because they are larger and rotate more slowly than the compact galaxies.

These galaxies are ideal targets for the Wide Field Camera 3, which is scheduled to be installed aboard Hubble during Servicing Mission 4 in the fall of 2008. “We hope to use the Wide Field Camera 3 to find thousands of these galaxies. The Hubble images, together with the laser guide star adaptive optics system at Keck Observatory, should lead to a better understanding of the evolution of galaxies early in the life of the universe,” said Garth Illingworth of the University of California, Santa Cruz, and Lick Observatory.

The findings appeared in the April 10, 2008 issue of the Astrophysical Journal Letters.

The authors of the science paper are Pieter van Dokkum (Yale University), Marijn Franx (Leiden University, The Netherlands), Mariska Kriek (Princeton University), Bradford Holden, Garth Illingworth, Daniel Magee, and Rychard Bouwens (University of California, Santa Cruz and Lick Observatory), Danilo Marchesini (Yale University), Ryan Quadri (Leiden University), Greg Rudnick (National Optical Astronomical Observatory, Tucson), Edward Taylor (Leiden University), and Sune Toft (European Southern Observatory, Germany).

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA) and is managed by NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Md. The Space Telescope Science Institute (STScI) conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, DC.

The W. M. Keck Observatory (http://www.keckobservatory.org) is operated by the California Association for Research in Astronomy (CARA), a non-profit 501 (c) (3) corporation whose governing board consists of directors from the California Institute of Technology and the University of California. Made possible by grants totaling $138 million from the W. M. Keck Foundation, the Observatory began operations in 1992 and today has a base budget of $12 million, augmented by various grants, contracts and private donations which totaled $14M in FY07.

Water Vapor Detected in Protoplanetary Disks

PASADENA, Calif.—Water is an essential ingredient for forming planets, yet has remained hidden from scientists searching for it in protoplanetary systems, the spinning disks of particles surrounding newly formed stars where planets are born. Now the detection of water vapor in the inner part of two extrasolar protoplanetary disks brings scientists one step closer to understanding water’s role during terrestrial planet formation.

By maximizing the spectroscopic capabilities of NASA’s Spitzer Space Telescope and high-resolution measurements from the Keck II Telescope in Hawaii, researchers from the California Institute of Technology and other institutes found water molecules in disks of dust and gas around two young stars. DR Tau and AS 205A, respectively around 457 and 391 light-years away from Earth, are each at the center of a spinning disk of particles that may eventually coalesce to form planets.

“This is one of the very few times that water vapor has been detected in the inner part of a protoplanetary disk—the most likely place for terrestrial planets to form,” says Colette Salyk, a graduate student in geological and planetary sciences at Caltech. She is the lead author of a group of scientists reporting their findings in the March 20 issue of the Astrophysical Journal Letters.

Salyk and her colleagues first harnessed light-emission data captured by Spitzer to inspect dozens of young stars with protoplanetary disks. They honed in on DR Tau and AS 205A because these presented a large number of water emission lines—spikes of brightness at certain wavelengths that are a unique fingerprint for water vapor. “Only Spitzer is capable of observing these particular lines in a large number of disks because it operates above Earth’s obscuring water-vapor-rich atmosphere,” says Salyk.

To determine in what part of the disk the vapor resides, the team made high-resolution measurements at shorter wavelengths with NIRSPEC, the Near-InfraRed cross-dispersed echelle grating Spectrometer for the Keck II Telescope. Unlike Spitzer, which observed water lines blended together into clumps, NIRSPEC can resolve individual water lines in selected regions where the atmospheric transmission is good. The shape of each line relays information on the velocity of the molecules emitting the light. “They were moving at fast speeds,” says Salyk, “indicating that they came from close to the stars, which is where Earthlike planets might be forming.”

“While we don’t detect nearly as much water as exists in the oceans on Earth, we see only a very small part of the disk—essentially only its surface—so the implication is that the water is quite abundant,” remarks coauthor Geoffrey Blake, professor of cosmochemistry and planetary sciences and professor of chemistry at Caltech.

The presence of water in the inner disk may indicate its stage on the road to planet formation. A planet like Jupiter in our solar system grew as its gravitational field trapped icy solids spinning in the outer part of the sun’s planetary disk. However, before Jupiter gained much mass, these same icy solids could have traveled towards the star and evaporated to produce water vapor such as that seen around DR Tau and AS 205A.

Although they have not detected icy solids in the extrasolar disks, says Salyk, “our observations are possible evidence for the migration of solids in the disk. This is an important prediction of planet-forming models.”

These initial observations portend more to come, says coauthor Klaus Pontoppidan, a Caltech Hubble Postdoctoral Scholar in Planetary Science. “We were surprised at how easy it is to find water in planet-forming disks once we had learned where to look. It will take years of work to understand the details of what we see.”

This is “a much larger story than just one or two disks,” Blake adds. “With upcoming observations of tens of young stars and disks with both Spitzer and NIRSPEC, along with our data in hand, we can construct a story for how water concentrations evolve in disks, and hopefully answer questions like how Earth acquired its oceans.”

Contact: Elisabeth Nadin (626) 395-3631 .(JavaScript must be enabled to view this email address)

NOVA PHENOMENON EXPLAINED WITH NULLING MODE AT KECK OBSERVATORY

MAUNA KEA (January 28th, 2008) First results from a new scientific instrument at W. M. Keck Observatory are helping scientists understand the physics behind recurrent novae, a type of cataclysmic star system. The results are overturning long-standing assumptions about powerful explosions called novae and have produced the first unified model for a nearby nova called RS Ophiuchi.

“We were getting ready for a routine engineering run when all of a sudden the nova went off. It was very bright and easy to observe, so we took this opportunity and turned it into gold,” says team member Marc Kuchner of NASA’s Goddard Space Flight Center in Greenbelt, Md.

The “nulling” mode of the Keck Interferometer is part of the NASA-funded Keck Interferometer, which combines starlight using two 10-meter (33 feet) telescopes. In this mode, the interferometer suppresses the blinding light of a star so researchers can study the surrounding environment. The instrument helps researchers observe very faint objects near bright sources and produces ten times more resolving power than a single Keck telescope working alone. It is the only instrument of its kind in operation.

The nulling mode was developed to search for dust around nearby stars, which make finding planets around these stars more difficult. “If the dust were by itself, it would be easy to detect with Keck,” explains Dr. Rachel L. Akeson, Keck Interferometer project scientist at the Michelson Science Center at Caltech. “But the star is so much brighter, that something has to be done to block the light, which is what the nuller does. But this technique turns out to be useful for lots of other kinds of objects, including this one, where dust is near a star that just went nova.”

The Keck Nuller was undergoing tests February 12, 2006, when a nova flared up in the constellation Ophiuchus. The system, known as RS Ophiuchi, consists of a white dwarf and a red giant. The red giant is gradually shedding its massive gaseous outer layers, and the white dwarf is sweeping up much of this wind, growing in mass over time. As the matter builds up on the white dwarf’s surface it eventually reaches a critical point that ignites a thermonuclear explosion that causes the system to brighten 600-fold. RS Ophiuchi was previously seen to blow its stack in 1898, 1933, 1958, 1967, and 1985, so astronomers were eagerly anticipating the 2006 eruption.

Just 3.8 days after the nova was detected, the group observed the explosion with the Keck Nuller. The team set the instrument to cancel out the nova’s light, allowing the group to see the much fainter surrounding material. The group next adjusted the nuller to observe the extremely bright blast zone.

The instrument’s versatility was key to a surprising discovery. The nuller saw no dust in the bright zone, presumably because the nova’s blast wave vaporized dust particles. But farther from the white dwarf, at distances starting around 20 times the Earth-Sun distance, the nuller recorded the spectral signature of silicate dust. The blast wave had not yet reached this zone, so the dust must have pre-dated the explosion.

“This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” says Richard Barry of NASA Goddard, lead author of a paper on the Keck observations that will be published in the Astrophysical Journal. The team thinks the dust is created as the white dwarf plows through the red giant’s wind, creating a pinwheel pattern of higher-density regions that is reminiscent of galaxy spiral arms. Inside these spiral arms, atoms reach low enough temperatures and high enough densities to allow atoms to stick together to form dust particles. The nova’s blast wave has since destroyed RS Ophiuchi’s pinwheel pattern, but it should re-form over the next few years, and future Spitzer Space Telescope observations could see it.

Most studies of RS Ophiuchi have relied on spectroscopic models, but those methods have not been able to distinguish various nova components with as much detail as the interferometer. The Keck Nuller measured one component of the RS Ophiuchi system to an accuracy of just 4 milliarcseconds, or about the size of a basketball at 7,500 miles. The findings led to a new physical model of the system.

Barry is also coauthor of a paper based on Spitzer observations of RS Ophiuchi. This paper, which appeared in the December 20, 2007 issue of Astrophysical Journal, reports independent evidence for silicate dust that predates the 2006 explosion.

“The RS Ophiuchi observations are just a small taste of the power and potential we expect from the Keck Nuller,” says coauthor William Danchi of NASA Goddard. “But ultimately we want to launch a nulling interferometer into space to image extrasolar planets. These Keck results are a technological and scientific pathfinder toward that future.”

The paper, “Milliarcsecond N-Band Observations of the Nova RS Ophiuchi: First Science with the Keck Interferometer Nuller” will be published in the May 1st issue of the Astrophysical Journal, with co-authors from Goddard, Jet Propulsion Laboratory, Michelson Science Center, W. M. Keck Observatory and Columbia University.

Observations were conducted at the W. M. Keck Observatory (http://www.keckobservatory.org) in Hawaii, a non-profit 501 (c) (3) organization. The Michelson Science Center manages the Keck Interferometer’s science operations for NASA’s Science Mission Directorate from its offices at Caltech in coordination with the Jet Propulsion Laboratory. The W. M. Keck Observatory is governed by a board of directors from the California Institute of Technology and the University of California. In addition, the National Aeronautics and Space Administration and the W. M. Keck Foundation each have liaisons to the board. Construction of the twin Keck telescopes and domes was made possible with generous grants totaling more than $140 million from the W. M. Keck Foundation in Los Angeles. For more information about the Keck Interferometer Nuller, visit: http://msc.caltech.edu/ missions/KI/.

Astrophysical Journal preprint: Milliarcsecond N-Band Observations of the Nova RS Ophiuchi: First Science with the Keck Interferometer Nuller