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  • richardmitnick 4:19 pm on May 14, 2015 Permalink | Reply
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    From Keck: “Scientists at Keck Discover the Fluffiest Galaxies” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    May 14, 2015
    No Writer Credit

    1
    A collection of unidentified blobs was discovered toward the Coma clusterof galaxies, using the Dragonfly Telephoto Array. One of these puzzling objects, Dragonfly 44, was studied in detail using the Keck Observatory and confirmed as an ultra-diffuse galaxy. Even though it is 60,000 light years across, It is so far away that it appears as only a faint smudge. Credit: P. van Dokkum, R. Abraham, J. Brodie

    2
    Reconstructed spectrum of light spread out from the ultra-diffuse galaxy, DragonFly44, as seen by the Keck/LRIS instrument. Dark bands occur where atoms and molecules absorb the galaxy’s starlight. These bands reveal the compositions and ages of the stars, and also the distance of the galaxy. Credit: P. van Dokkum, A. Romanowsky, J. Brodie

    3
    An ultra-diffuse galaxy, Dragonfly 17, is shown next to other types of galaxies, to scale. The Andromeda galaxy is a giant spiral like our own Milky Way, and a dwarf elliptical galaxy, NGC 205, is also shown. Ultra-diffuse galaxies have the same number of stars as dwarf ellipticals, but spread out over a much larger region. Credit: B. Schoening, V. Harvey/REU program/NOAO/AURA/NSF, P. van Dokkum/Hubble Space Telescope.

    An international team of researchers led by Pieter van Dokkum at Yale University have used the W. M. Keck Observatory to confirm the existence of the most diffuse class of galaxies known in the universe. These “fluffiest galaxies” are nearly as wide as our own Milky Way galaxy – about 60,000 light years – yet harbor only one percent as many stars. The findings were recently published in the Astrophysical Journal Letters.

    “If the Milky Way is a sea of stars, then these newly discovered galaxies are like wisps of clouds”, said van Dokkum. “We are beginning to form some ideas about how they were born and it’s remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter ‘shields’ that are protecting them from this intergalactic assault.”

    The team made the latest discovery by combining results from one of the world’s smallest telescopes as well as the largest telescope on Earth. The Dragonfly Telephoto Array used 14-centimeter state of the art telephoto lens cameras to produce digital images of the very faint, diffuse objects.

    U Toronto Dunlap Dragonfly telescope Array
    U Toronto Dunlap Institute Dragonfly telescope Array

    Keck Observatory’s 10-meter Keck I telescope, with its Low Resolution Imaging Spectrograph, then separated the light of one of the objects into colors that diagnose its composition and distance.

    Finding the distance was the clinching evidence. The data from Keck Observatory showed the diffuse “blobs” are very large and very far away, about 300 million light years, rather than small and close by. The blobs can now safely be called Ultra Diffuse Galaxies (UDGs).

    “If there are any aliens living on a planet in an ultra-diffuse galaxy, they would have no band of light across the sky, like our own Milky Way, to tell them they were living in a galaxy. The night sky would be much emptier of stars,” said team member Aaron Romanowsky, of San Jose State University.

    The UDGs were found in an area of the sky called the Coma cluster , where thousands of galaxies have been drawn together in a mutual gravitational dance.

    5
    A Sloan Digital Sky Survey [SDSS]/Spitzer Space Telescope mosaic of the Coma Cluster in long-wavelength infrared (red), short-wavelength infrared (green), and visible light. The many faint green smudges are dwarf galaxies in the cluster. Credit: NASA/JPL-Caltech/GSFC/SDSS

    Sloan Digital Sky Survey Telescope
    SDSS telescope

    NASA Spitzer Telescope
    NASA/Spitzer

    “Our fluffy objects add to the great diversity of galaxies that were previously known, from giant ellipticals that outshine the Milky Way, to ultra compact dwarfs,” said University of California, Santa Cruz Professor Jean Brodie.

    “The big challenge now is to figure out where these mysterious objects came from,” said Roberto Abraham, of the University of Toronto. “Are they ‘failed galaxies’ that started off well and then ran out of gas? Were they once normal galaxies that got knocked around so much inside the Coma cluster that they puffed up? Or are they bits of galaxies that were pulled off and then got lost in space?”

    The key next step in understanding UDGs is to to pin down exactly how much dark matter they have. Making this measurement will be even more challenging than the latest work.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

    The Low Resolution Imaging Spectrometer (LRIS) is a very versatile visible-wavelength imaging and spectroscopy instrument commissioned in 1993 and operating at the Cassegrain focus of Keck I. Since it has been commissioned it has seen two major upgrades to further enhance its capabilities: addition of a second, blue arm optimized for shorter wavelengths of light; and the installation of detectors that are much more sensitive at the longest (red) wavelengths. Each arm is optimized for the wavelengths it covers. This large range of wavelength coverage, combined with the instrument’s high sensitivity, allows the study of everything from comets (which have interesting features in the ultraviolet part of the spectrum), to the blue light from star formation, to the red light of very distant objects. LRIS also records the spectra of up to 50 objects simultaneously, especially useful for studies of clusters of galaxies in the most distant reaches, and earliest times, of the universe.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
    • kagmi 5:29 pm on May 14, 2015 Permalink | Reply

      It’s a rather incredible perspective to think of thousands of galaxies whizzing around hitting each other. Wrapping one’s head around our own solar system is mind-boggling enough; and ours is but one star of one-hundred billion in a single galaxy!

      There are more things in Heaven and on Earth…

      Like

    • richardmitnick 6:14 pm on May 14, 2015 Permalink | Reply

      Galaxies rarely actually interact. When they do, there is still mostly empty space, the stars practically never touch each other.

      Like

  • richardmitnick 2:55 pm on May 14, 2015 Permalink | Reply
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    From UCSC: “Against all odds: Astronomers baffled by discovery of rare quasar quartet” 

    UC Santa Cruz

    UC Santa Cruz

    May 14, 2015
    Tim Stephens (UCSC) & Markus Possel (MPIA)

    1
    Arrows indicated the four quasars in this image. The quasars are embedded in a giant nebula of cool dense gas, visible as a blue haze, which has an extent of one million light-years across. This false-color image is based on observations with the Keck I telescope in Hawaii. (Image Credit: Hennawi & Arrigoni-Battaia, MPIA)

    A team of astronomers including J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz, has discovered the first known quasar quartet: four quasars, each one a rare object in its own right, in close physical proximity to each other. The quartet resides in one of the most massive structures ever discovered in the distant universe (a “proto-cluster” of galaxies) and is surrounded by a giant nebula of cool dense gas.

    The findings, published May 15 in Science, are based on observations using the 10-meter Keck I Telescope at the W. M. Keck Observatory in Hawaii.

    Keck Observatory
    Keck

    Either the discovery is a one-in-ten-million coincidence, or cosmologists need to rethink their models of quasar evolution and the formation of the most massive cosmic structures, according to first author Joseph Hennawi of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany.

    Exceedingly rare

    Quasars constitute a brief phase of galaxy evolution, powered by the accretion of matter onto a supermassive black hole at the center of a galaxy. During this phase, they are the most luminous objects in the universe, shining hundreds of times brighter than their host galaxies, which themselves contain hundreds of billions of stars. But these hyper-luminous episodes last only a tiny fraction of a galaxy’s lifetime. As a result, quasars are exceedingly rare and are typically separated by hundreds of millions of light years from one another. The researchers estimate that the odds of discovering a quadruple quasar by chance is one in ten million.

    How did they get so lucky? Clues come from peculiar properties of the quartet’s environment. The four quasars are surrounded by a giant nebula of cool dense hydrogen gas, which emits light because it is irradiated by the intense glare of the quasars. In addition, both the quartet and the surrounding nebula reside in an unusual region of the universe with a surprisingly large amount of matter.

    “There are several hundred times more galaxies in this region than you would expect to see at these distances,” said Prochaska, the principal investigator of the Keck observations.

    Proto-cluster

    Given the exceptionally large number of galaxies, this system resembles the massive agglomerations of galaxies known as galaxy clusters that astronomers observe in the present-day universe. But because the light from this cosmic metropolis has been travelling for 10 billion years before reaching Earth, the images show the region as it was 10 billion years ago, less than 4 billion years after the big bang. It is thus an example of a proto-cluster, the progenitor or ancestor of a present-day galaxy cluster.

    Piecing all of these anomalies together, the researchers tried to understand what appears to be their incredible stroke of luck. “If you discover something which, according to current scientific wisdom, should be extremely improbable, you can come to one of two conclusions: either you just got very lucky, or you need to modify your theory,” Hennawi said.

    The researchers speculate that some physical process might make quasar activity much more likely in certain environments. One possibility is that quasar episodes are triggered when galaxies collide or merge, because these violent interactions efficiently funnel gas onto the central black hole. Such encounters are much more likely to occur in a dense proto-cluster filled with galaxies, just as one is more likely to encounter traffic when driving through a big city.

    “The giant emission nebula is an important piece of the puzzle, since it signifies a tremendous amount of dense cool gas,” said coauthor Fabrizio Arrigoni-Battaia of MPIA. Supermassive black holes can only shine as quasars if there is gas for them to swallow, and an environment that is gas rich could provide favorable conditions for fueling quasars.

    Unexpected

    On the other hand, given the current understanding of how massive structures in the universe form, the presence of the giant nebula in the proto-cluster is totally unexpected, according to coauthor Sebastiano Cantalupo of UC Santa Cruz and ETH Zurich. “Our current models of cosmic structure formation based on supercomputer simulations predict that massive objects in the early universe should be filled with rarefied gas that is about ten million degrees, whereas this giant nebula requires gas thousands of times denser and colder,” he said.

    The discovery of the first quadruple quasar may force cosmologists to rethink their models of quasar evolution and the formation of the most massive structures in the universe.

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

     
    • kagmi 5:40 pm on May 14, 2015 Permalink | Reply

      *blink* *blink* I’m still wrapping my head around the idea of a nebula large enough to surround SEVERAL galaxies.

      Like

    • richardmitnick 6:12 pm on May 14, 2015 Permalink | Reply

      Nebulae can be beyond immense. The Carina Nebula is three light years tall. That is a lot of space. A light year is a distance of 6 trillion miles.

      Like

  • richardmitnick 12:48 pm on May 5, 2015 Permalink | Reply
    Tags: , , Keck Observatory   

    From Keck: “Scientists at Keck Measure Farthest Galaxy Ever” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808.881.3827

    1
    Credit: NASA, ESA, P. Oesch and I. Momcheva (Yale University), and the 3D-HST and HUDF09/XDF Teams
    The farthest confirmed galaxy observed to date. It was identified in this Hubble image of a field of galaxies in the CANDELS survey (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey). The W. M. Keck Observatory obtained a spectroscopic redshift (z=7.7), extending the previous redshift record. This is the most distant confirmed galaxy known, and it appears to also be one of the most massive sources at that time. The inset image of the galaxy is blue, suggesting very young stars.

    An international team of astronomers, led by Yale and the University of California, Santa Cruz, pushed back the cosmic frontier of galaxy exploration to a time when the Universe was only five percent of its present age. The team discovered an exceptionally luminous galaxy more than 13 billion years in the past and determined its exact distance from Earth using the powerful MOSFIRE instrument on the 10-meter Keck I telescope at the W. M. Keck Observatory in Hawaii.

    Keck MOSFIRE
    MOSFIRE

    These observations confirmed it to be the most distant galaxy ever measured, setting a new record. The findings are being published in Astrophysical Journal Letters today.

    The galaxy, EGS-zs8-1, is one of the brightest and most massive objects in the early universe and was originally identified based on its particular colors in images from NASA’s Hubble and Spitzer Space Telescopes.

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Spitzer Telescope
    NASA/Spitzer

    “While we saw the galaxy as it was 13 billion years ago, it had already built more than 15 percent of the mass of our own Milky Way today,” said Pascal Oesch of the Yale University, the lead author of the study. “But it had only 670 million years to do so. The universe was still very young then.” The new distance measurement also enabled the astronomers to determine that EGS-zs8-1 was still forming stars very rapidly, about 80 times faster than our galaxy today.

    Only a handful of galaxies currently have accurate distances measured in this epoch of the Universe and none younger than this.

    “Every confirmation adds another piece to the puzzle of how the first generations of galaxies formed in the early universe,” said Pieter van Dokkum of the Yale University, second author of the study. “Only the largest telescopes are powerful enough to reach to these large distances.”

    The discovery was only possible thanks to the relatively new MOSFIRE instrument on the Keck I telescope, which allows astronomers to efficiently study several galaxies at the same time.

    Measuring galaxies at these extreme distances and characterizing their properties is a main goal of astronomy over the next decade. The observations see EGS-zs8-1 at a time when the Universe was undergoing very important changes: the hydrogen between galaxies was transitioning from a neutral to an ionized state.

    “It appears that the young stars in the early galaxies like EGS-zs8-1 were the main drivers for this transition called reionization”, said Rychard Bouwens of the Leiden Observatory, co-author of the study.

    These new Keck Observatory, Hubble, and Spitzer observations together also pose new questions. They confirm that massive galaxies already existed early in the history of the Universe, but that their physical properties were very different from galaxies seen around us today. Astronomers now have very strong evidence that the peculiar colors of early galaxies seen in the Spitzer Space Telescope images originate from a very rapid formation of massive, young stars, which interacted with the primordial gas in these galaxies.

    MOSFIRE (Multi-Object Spectrograph for Infrared Exploration) is a highly-efficient instrument that can take images or up to 46 simultaneous spectra. Using a sensitive state-of-the-art detector and electronics system, MOSFIRE obtains observations fainter than any other near infrared spectrograph. MOSFIRE is an excellent tool for studying complex star or galaxy fields, including distant galaxies in the early Universe, as well as star clusters in our own Galaxy. MOSFIRE was made possible by funding provided by the National Science Foundation and astronomy benefactors Gordon and Betty Moore.

    Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 12:43 pm on April 29, 2015 Permalink | Reply
    Tags: , , , Keck Observatory   

    From Keck: “The Dark Matter Conspiracy” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    April 29, 2015
    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808.881.3827

    1
    Example of mapping out and analyzing the speeds of stars in an elliptical galaxy. Blue colors show regions where the stars are hurtling toward the observer on Earth, and red colors show regions that are moving away, in an overall pattern of coherent rotation. The top panel shows the original data, as collected using the DEIMOS spectrograph at the W.M. Keck Observatory. The bottom panel shows a numerical model that matches the data remarkably well, from using the combined gravitational influence of luminous and dark matter. Credit: M. Cappellari and the SLUGGS team

    2
    The speeds of stars on circular orbits have been measured around both spiral and elliptical galaxies. Without dark matter, the speeds should decrease with distance from the galaxy, at different rates for the two galaxy types. Instead, the dark matter appears to conspire to keep the speeds steady. Credit: M. Cappellari and the Sloan Digital Sky Survey

    3
    Computer simulation of a galaxy, with the dark matter colorized to make it visible. The dark matter surrounds and permeates the galaxy, holding it together and allowing stars and planets to form. Credit: Springel et al., Virgo Consortium, Max-Planck-Institute for Astrophysics

    An international team of astronomers, led by Michele Cappellari from the University of Oxford, has used data gathered by the W. M. Keck Observatory in Hawaii to analyze the motions of stars in the outer parts of elliptical galaxies, in the first such survey to capture large numbers of these galaxies. The team discovered surprising gravitational similarities between spiral and elliptical galaxies, implying the influence of hidden forces. The study will be published in The Astrophysical Journal Letters.

    The scientists from the USA, Australia, and Europe used the powerful DEIMOS spectrograph installed on the world’s largest optical telescope at Keck Observatory to conduct a major survey of nearby galaxies called SLUGGS, which mapped out the speeds of their stars.

    Keck DEIMOS
    DEIMOS spectrograph

    The team then applied Newton’s law of gravity to translate these speed measurements into the amounts of matter distributed within the galaxies.

    “The DEIMOS spectrograph was crucial for this discovery since it can take in data from an entire giant galaxy all at once, while at the same time sampling the speeds of its stars at a hundred separate locations with exquisite accuracy,” said Aaron Romanowsky, of San Jose State University.

    One of the most important scientific discoveries of the 20th century was that the spectacular spiral galaxies, such as our own Milky Way, rotate much faster than expected, powered by an extra gravitational force of invisible “dark matter” as it is now called. Since this discovery 40 years ago, we have learned that this mysterious substance, which is probably an exotic elementary particle, makes up about 85 percent of the mass in the Universe, leaving only 15 percent to be the ordinary stuff encountered in our everyday lives. Dark matter is central to our understanding of how galaxies form and evolve – and is ultimately one of the reasons for the existence of life on Earth – yet we know almost nothing about it.

    “The surprising finding of our study was that elliptical galaxies maintain a remarkably constant circular speed out to large distances from their centers, in the same way that spiral galaxies are already known to do,” said Cappellari. “This means that in these very different types of galaxies, stars and dark matter conspire to redistribute themselves to produce this effect, with stars dominating in the inner regions of the galaxies, and a gradual shift in the outer regions to dark matter dominance.”

    However, the conspiracy does not come out naturally from models of dark matter, and some disturbing fine-tuning is required to explain the observations. For this reason, the conspiracy even led some authors to suggest that, rather than being due to dark matter, it may be due to Newton’s law of gravity becoming progressively less accurate at large distances. Remarkably, decades after it was proposed, this alternative theory (without dark matter) still cannot be conclusively ruled out.

    Spiral galaxies only constitute less than half of the stellar mass in the Universe, which is dominated by elliptical and lenticular galaxies, and which have puffier configurations of stars and lack the flat disks of gas that spirals have. In these galaxies, it has been very difficult technically to measure their masses and to find out how much dark matter they have, and how this is distributed – until now.

    Because the elliptical galaxies have different shapes and formation histories than spiral galaxies, the newly discovered conspiracy is even more profound and will lead experts in dark matter and galaxy formation to think carefully about what has happened in the “dark sector” of the universe.

    “This question is particularly timely in this period when physicists at CERN are about to restart the Large Hadron Collider to try to directly detect the same elusive dark matter particle, which makes galaxies rotate fast, if it really exists!,” said Professor Jean Brodie, principal investigator of the SLUGGS survey.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

    DEIMOS (the DEep Imaging and Multi-Object Spectrograph) boasts the largest field of view (16.7 arcmin by 5 arcmin) of any of the Keck instruments, and the largest number of pixels (64 Mpix). It is used primarily in its multi-object mode, obtaining simultaneous spectra of up to 130 galaxies or stars. Astronomers study fields of both nearby and distant galaxies with DEIMOS, efficiently probing the most distant corners of the universe with high sensitivity.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 8:54 pm on April 28, 2015 Permalink | Reply
    Tags: , , Keck Observatory, Robotic telescopes   

    From Keck: “Robot Discovers Two New Neighbors” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    April 28, 2015
    MEDIA CONTACT:
    Steve Jefferson
    sjefferson@keck.hawaii.edu
    +1 808-881-3827

    SCIENCE CONTACTS
    BJ Fulton
    bfulton@hawaii.edu
    +1 408-528-4858

    Dr. Andrew Howard
    howard@ifa.hawaii.edu
    +1 808-208-1224

    A team of astronomers using ground-based telescopes in Hawaii, California, and Arizona recently discovered a planetary system orbiting a nearby star that is only 54 light-years away. All three planets orbit their star at a distance closer than Mercury orbits the sun, completing their orbits in just 5, 15, and 24 days. The paper is being published in the Astrophysical Journal.

    Astronomers from the University of Hawaii at Manoa, the University of California, Berkeley, the University of California Observatories, and Tennessee State University found the planets using measurements from the W. M. Keck Observatory on Maunakea, Hawaii, the Automated Planet Finder (APF) Telescope at Lick Observatory in California and the Automatic Photometric Telescope (APT) at Fairborn Observatory in Arizona.

    Lick Automated Planet Finder telescope
    Lick APF

    2
    APT farm managed by Lou Boyd atop Mt Hopkins in Arizona.

    The team discovered the new planets by detecting the wobble of the star HD 7924 as the planets orbited and pulled on the star gravitationally. APF and Keck Observatory traced out the planets’ orbits over many years using the Doppler technique that has successfully found hundreds of mostly larger planets orbiting nearby stars. APT made crucial measurements of the brightness of HD 7924 to assure the validity of the planet discoveries.

    The Keck Observatory found the first evidence of planets orbiting HD 7924, discovering the innermost planet in 2009 using the HIRES instrument installed on the 10-meter Keck I telescope.

    Keck HIRES
    HIRES

    This same combination was also used to find other super-Earths orbiting nearby stars in planet searches led by UH astronomer Andrew Howard and UC Berkeley Professor Geoffrey Marcy. It took five years of additional observations at Keck Observatory and the year-and-a-half campaign by the APF Telescope to find the two additional planets orbiting HD 7924.

    The new APF facility offers a way to speed up the planet search. Planets can be discovered and their orbits traced much more quickly because APF is a dedicated facility that robotically searches for planets every clear night. Training computers to run the observatory all night, without human oversight, took years of effort by the University of California Observatories staff and graduate students on the discovery team.

    “We initially used APF like a regular telescope, staying up all night searching star to star. But the idea of letting a computer take the graveyard shift was more appealing after months of little sleep. So we wrote software to replace ourselves with a robot,” said University of Hawaii graduate student BJ Fulton.

    The Kepler Space Telescope has discovered thousands of extrasolar planets and demonstrated that they are common in our Milky Way galaxy.

    NASA Kepler Telescope
    Kepler

    However, nearly all of these planets are far from our solar system. Most nearby stars have not been thoroughly searched for the small “super-Earth” planets (larger than Earth but smaller than Neptune) that Kepler found in great abundance.

    This discovery shows the type of planetary system that astronomers expect to find around many nearby stars in the coming years. “The three planets are unlike anything in our solar system, with masses 7-8 times the mass of Earth and orbits that take them very close to their host star,” explains UC Berkeley graduate student Lauren Weiss.

    “This level of automation is a game-changer in astronomy,” Howard said. “It’s a bit like owning a driverless car that goes planet shopping.”

    Observations by APF, APT, and Keck Observatory helped verify the planets and rule out other explanations. “Starspots, like sunspots on the sun, can momentarily mimic the signatures of small planets. Repeated observations over many years allowed us to separate the starspot signals from the signatures of these new planets,” said Evan Sinukoff, a UH graduate student who contributed to the discovery.

    The robotic observations of HD 7924 are the start of a systematic survey for super-Earth planets orbiting nearby stars. Fulton will lead this two-year search with the APF as part of his research for his doctoral dissertation. “When the survey is complete we will have a census of small planets orbiting sun-like stars within approximately 100 light-years of Earth,” Fulton said.

    Telescope automation is relatively new to astronomy, and UH astronomers are building two forefront facilities. Christoph Baranec built the Robo-AO observatory to takes high-resolution images using a laser to remove the blur of Earth’s atmosphere, and John Tonry is developing ATLAS, a robotic observatory that will hunt for killer asteroids.

    Caltech Robo-AO
    Robo-AO

    The paper presenting this work, Three super-Earths orbiting HD 7924, is available at no cost here. The other authors of the paper are Howard Isaacson (UC Berkeley), Gregory Henry (TSU), and Bradford Holden and Robert I. Kibrick (UCO).

    In honor of the donations of Gloria and Ken Levy that helped facilitate the construction of the Levy spectrograph on APF and supported Lauren Weiss, the team has informally named the HD 7924 system the “Levy Planetary System.” The team also acknowledges the support of NASA, the U.S. Naval Observatory, and the University of California for its support of Lick Observatory.

    HIRES (the High-Resolution Echelle Spectrometer) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. It does this by separating the light into many “stripes” of spectra stacked across a mosaic of three large CCD detectors. HIRES is famous for finding planets orbiting other stars. Astronomers also use HIRES to study distant galaxies and quasars, finding clues to the Big Bang. 


    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 7:27 pm on March 19, 2015 Permalink | Reply
    Tags: , , , Keck Observatory   

    From Keck: “Unusual Asteroid Suspected of Spinning to Explosion” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    March 19, 2015
    Steve Jefferson
    Communications Officer
    W. M. Keck Observatory
    808.881.3827
    sjefferson@keck.hawaii.edu

    1
    Credit: M. Drahus, W. Waniak (OAUJ) / W. M. Keck Observatory
    Active asteroid P/2012 F5 captured by Keck II/DEIMOS in mid-2014. Top panel shows a wide-angle view of the main nucleus and smaller fragments embedded in a long dust trail. Bottom panel shows a close-up view with the trail numerically removed to enhance the visibility of the fragments.

    A team led by astronomers from the Jagiellonian University in Krakow, Poland, recently used the W. M. Keck Observatory in Hawaii to observe and measure a rare class of “active asteroids” that spontaneously emit dust and have been confounding scientists for years. The team was able to measure the rotational speed of one of these objects, suggesting the asteroid spun so fast it burst, ejecting dust and newly discovered fragments in a trail behind it. The findings are being published in Astrophysical Journal Letters on March 20, 2015.

    2
    Credit: M. Drahus, W. Waniak (OAUJ) / W. M. Keck Observatory
    Brightness fluctuations of the nucleus of P/2012 F5 during two consecutive rotation cycles. Presented versus time (top panel) and versus the nucleus rotation phase (bottom panel).

    Unlike the hundreds of thousands of asteroids in the main belt of our solar system, which move cleanly along their orbits, active asteroids were discovered several years ago mimicking comets with their tails formed by calm, long lasting ice sublimation.

    Then in 2010 a new type of active asteroid was discovered, which ejected dust like a shot without an obvious reason. Scientists gravitated around two possible hypotheses. One states the explosion is a result of a hypervelocity collision with another minor object. The second popular explanation describes it as a consequence of “rotational disruption”, a process of launching dust and fragments by spinning so fast, the large centrifugal forces produced exceed the object’s own gravity, causing it to break apart. Rotational disruption is the expected final state of what is called the YORP effect – a slow evolution of the rotation rate due to asymmetric emission of heat.

    To date, astronomers have identified four objects suspected of either collision- or rotation-driven activity. These four freakish asteroids are all very small, at a kilometer or less, which makes them unimaginably faint when viewed from a typical distance of a couple hundred million miles. Despite prior attempts, the tiny size of the objects kept scientists from determining some of the key characteristics that could prove or disprove the theories.

    Until last August, when the team led by Michal Drahus of the Jagiellonian University was awarded time at Keck Observatory.

    “When we pointed Keck II at P/2012 F5 last August, we hoped to measure how fast it rotated and check whether it had sizable fragments. And the data showed us all that,” Drahus said.

    The team discovered at least four fragments of the object, previously established to have impulsively ejected dust in mid-2011. They also measured a very short rotation period of 3.24 hours – fast enough to cause the object impulsively explode.

    “This is really cool because fast rotation has been suspected of catapulting dust and triggering fragmentation of some active asteroids and comets. But up until now we couldn’t fully test this hypothesis as we didn’t know how fast fragmented objects rotate,” Drahus said.

    The astronomers calculated the object’s rotation period by measuring small periodic fluctuations in brightness. Such oscillations occur naturally as the irregular nucleus rotates about its spin axis and reflects different amounts of sunlight during a rotation cycle.

    “This is a well-established technique but its application on faint targets is challenging,” said Waclaw Waniak of the Jagiellonian University who processed the Keck Observatory data. “The main difficulty is the brightness must to be probed every few minutes so we don’t have time for long exposures. We needed the huge collecting area of Keck II, which captures a plentiful amount of photons in a very short time.”

    The photons were then concentrated in the telescope’s light path and sent to the DEIMOS instrument to produce the data that allowed the scientists to determine P/2012 F5’s nature. While monitoring brightness in the individual 3-minute exposures, scientists also compiled all the data to produce a single ultra-deep image, which revealed the fragments.

    The success wouldn’t be possible if the selected target, P/2012 F5, were not an ideal candidate for this study. Alex R. Gibbs discovered the object on March 22, 2012 with the Mount Lemmon 1.5 meter reflector. It was initially classified as a comet, based solely on its “dusty” look. But two independent teams quickly have shown all this dust was emitted in a single pulse about a year before the discovery – something that doesn’t happen to comets. When the dust settled in 2013, another team using the University of Hawaii’s 2.2-meter telescope on Mauna Kea detected a star-like nucleus and suggested a maximum size of 2 kilometers.

    “We suspected that this upper limit was close to the actual size of the object. Consequently, we chose to observe P/2012 F5 because – despite its small size – it appeared to be the largest and easiest to observe active asteroid suspected of rotational disruption,” said Jessica Agarwal of the Max Planck Institute for Solar System Research who chose P/2012 F5 as the subject.

    As a result of the study, P/2012 F5 is the first freshly fragmented object in the solar system with a well-determined spin rate, and this spin rate turns out to be the fastest among the active asteroids. A careful analysis made by the team shows that these two features of the object are consistent with the “rotational disruption” scenario. But alternative explanations, such as fragmentation due to an impact, cannot be completely ruled out.

    “There are many faster rotators among asteroids which don’t show signs of a recent mass loss. And there are many hypervelocity impactors straying out there and looking for targets to hit – be it a fast or slow rotator,” Drahus said.

    “We’re indebted to the Caltech Optical Observatories for generously awarding Keck Observatory time for this program,” said Drahus – formerly a NRAO Jansky Fellow at Caltech. “Without the huge collecting area of Keck II’s 10-meter mirror, we wouldn’t be able to achieve our goals so swiftly.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 3:36 pm on March 5, 2015 Permalink | Reply
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    From Keck: “Thermonuclear Supernova Ejects Galaxy’s Fastest Star” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    March 5, 2015
    Steve Jefferson
    Communications Officer
    W. M. Keck Observatory
    808.881.3827
    sjefferson@keck.hawaii.edu

    1
    An artist impression of the mass-transfer phase followed by a double-detonation supernova that leads to the ejection of US 708. While this illustration shows the supernova (bottom center) and the ejected star (left) at the same time, in reality the supernova would have been faded away long before the star reached that position.

    Scientists using the W. M. Keck Observatory and Pan-STARRS1 telescopes on Hawaii have discovered a star that breaks the galactic speed record, traveling with a velocity of about 1,200 kilometers per second or 2.7 million miles per hour. This velocity is so high, the star will escape the gravity of our galaxy. In contrast to the other known unbound stars, the team showed that this compact star was ejected from an extremely tight binary by a thermonuclear supernova explosion. These results will be published in the March 6 issue of Science.

    Pann-STARSR1 Telescope
    Pann-STARRS1 interior
    Pan-STARRS1

    Stars like the Sun are bound to our Galaxy and orbit its center with moderate velocities. Only a few so-called hypervelocity stars are known to travel with velocities so high that they are unbound, meaning they will not orbit the galaxy, but instead will escape its gravity to wander intergalactic space.

    A close encounter with the supermassive black hole at the centre of the Milky Way is typically presumed the most plausible mechanism for kicking these stars out of the galaxy.

    A team of astronomers led by Stephan Geier (European Southern Observatory, Garching) observed the known high-velocity star know as US 708 with the Echellette Spectrograph and Imager instrument on the 10-meter, Keck II telescope to measure its distance and velocity along our line of sight.

    Keck Eschellette Spectrograph
    Echellette Spectrograph and Imager instrument

    By carefully combining position measurements from digital archives with newer positions measured from images taken during the course of the Pan-STARRS1 survey, they were able to derive the tangential component of the star’s velocity (across our line of sight).

    Putting the measurements together, the team determined the star is moving at about 1,200 kilometers per second – much higher than the velocities of previously known stars in the Milky Way galaxy. More importantly, the trajectory of US 708 means the supermassive black hole at the galactic center could not be the source of US 708’s extreme velocity.

    US 708 has another peculiar property in marked contrast to other hypervelocity stars: it is a rapidly rotating, compact helium star likely formed by interaction with a close companion. Thus, US 708 could have originally resided in an ultra compact binary system, transferring helium to a massive white dwarf companion, ultimately triggering a thermonuclear explosion of a type Ia supernova. In this scenario, the surviving companion, i.e. US 708, was violently ejected from the disrupted binary as a result, and is now travelling with extreme velocity.

    These results provide observational evidence of a link between helium stars and thermonuclear supernovae, and is a step towards understanding the progenitor systems of these mysterious explosions.

    ESI (Echellette Spectrograph and Imager) is a medium-resolution visible-light spectrograph that records spectra from 0.39 to 1.1 microns in each exposure. Built at UCO/Lick Observatory by a team led by Prof. Joe Miller, ESI also has a low-resolution mode and can image in a 2 x 8 arcmin field of view. An upgrade provided an integral field unit that can provide spectra everywhere across a small, 5.7 x 4.0 arcsec field. Astronomers have found a number of uses for ESI, from observing the cosmological effects of weak gravitational lensing to searching for the most metal-poor stars in our galaxy.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 8:19 pm on January 16, 2015 Permalink | Reply
    Tags: , , Keck Observatory   

    From Keck: “Three Almost Earth-Size Planets Found Orbiting Nearby Star” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    January 16, 2015
    Steve Jefferson
    Communications Officer
    W. M. Keck Observatory
    808.881.3827
    sjefferson@keck.hawaii.edu

    Last week, a team of scientists discovered a system of three planets, each just larger than Earth, orbiting a nearby star called EPIC 201367065. The three planets are 1.5-2 times the size of Earth. The outermost planet orbits on the edge of the so-called “habitable zone,” where the temperature may be just right for liquid water, believed necessary to support life, on the planet’s surface. The paper, A Nearby M Star with Three Transiting Super-Earths Discovered by K2, was submitted to the Astrophysical Journal today and is available here.

    “The compositions of these newfound planets are unknown, but, there is a very real possibility the outer planet is rocky like Earth,” said Erik Petigura, a University of California, Berkeley graduate student who spent a year visiting the UH Institute for Astronomy. “If so, this planet could have the right temperature to support liquid water oceans.”

    The planets were confirmed by the NASA Infrared Telescope Facility (IRTF) the W. M. Keck Observatory in Hawaii as well as telescopes in California and Chile.

    NASA Infrared Telescope facility
    NASA IRTF

    “Keck’s contribution to this discovery was vital,” said Andrew Howard, a University of Hawaii astronomer on the team. “The adaptive optics image from NIRC2 showed the star hosting these three planets is a single star, not a binary. It showed that the planets are real and not an artifact of some masquerading multi-star system.”

    Keck NIRC2
    NIRC2

    Due to the competitive state of planet finding, and the fact that time on the twin Keck telescopes are scheduled months in advance, the team asked UC Berkeley Astronomer, Imke de Pater to gather some data during her scheduled run.

    “The collegiality of the Keck Observatory community is just wonderful,” Howard said. “Imke took time away from her own science observations to get us images of this system, all on a couple hours’ notice.”

    The new discovery paves the way for studies of the atmosphere of a warm planet nearly the size of Earth.

    “We’ve learned in the past year that planets the size and temperature of Earth are common in our Milky Way galaxy,” Howard said. “We also discovered some Earth-size planets that appear to be made of the same materials as our Earth, mostly rock and iron.”

    The astronomers next hope to determine what elements are in the planets’ atmospheres. If these warm, nearly Earth-size planets have thick, hydrogen-rich atmospheres, there is not much chance for life.

    “A thin atmosphere made of nitrogen and oxygen has allowed life to thrive on Earth. But nature is full of surprises. Many extrasolar planets discovered by the Kepler Mission are enveloped by thick, hydrogen-rich atmospheres that are probably incompatible with life as we know it,” said Ian Crossfield, the University of Arizona astronomer who led the study.

    NASA Kepler Telescope
    Kepler

    The discovery is all the more remarkable because Kepler is now hobbled by the loss of two reaction wheels that kept it pointing at a fixed spot in space. Kepler, launched in 2009, was reborn in 2014 as “K2” with a clever strategy of pointing the telescope in the plane of the Earth’s orbit to stabilize the spacecraft. Kepler is back to mining the cosmos for planets by searching for eclipses, or transits, as planets orbit in front of their host stars and periodically block some of the starlight.

    “I was devastated when Kepler was crippled by a hardware failure,” Petigura added. “It’s a testament to the ingenuity of NASA engineers and scientists that Kepler can still do great science.”

    Kepler sees only a small fraction of the planetary systems in its gaze, those with orbital planes aligned edge-on to our view from Earth. Planets with large orbital tilts are simply missed by Kepler.

    “It’s remarkable that the Kepler telescope is now pointed in the ecliptic, the plane that Earth sweeps out as it orbits the Sun,” Fulton explains. “This means that some of the planets discovered by K2 will have orbits lined up with Earth’s, a celestial coincidence that allows Kepler to see the alien planets, and Kepler-like telescopes in those very planetary systems (if there are any) to discover Earth.”

    “Here’s looking at you, looking at me,” said Howard.

    In addition to Howard and Petigura, UH graduate students Benjamin Fulton and Kimberly Aller, and UH astronomer Michael Liu were among the two dozen scientists who contributed to the study.

    NIRC2 (the Near-Infrared Camera, second generation) works in combination with the Keck II adaptive optics system to obtain very sharp images at near-infrared wavelengths, achieving spatial resolutions comparable to or better than those achieved by the Hubble Space Telescope at optical wavelengths. NIRC2 is probably best known for helping to provide definitive proof of a central massive black hole at the center of our galaxy. Astronomers also use NIRC2 to map surface features of solar system bodies, detect planets orbiting other stars, and study detailed morphology of distant galaxies.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

     
  • richardmitnick 9:37 pm on January 8, 2015 Permalink | Reply
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    From Keck: “Comprehensive Andromeda Study Hints of Violent History” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    January 8, 2015
    Media Contact:

    Steve Jefferson
    Communications Officer
    W. M. Keck Observatory
    808.881.3827
    sjefferson@keck.hawaii.edu

    Science Contacts:

    Claire Dorman
    UC Santa Cruz
    cdorman@ucolick.org

    Puragra (Raja) Guhathakurta
    (408) 455-3036
    UC Santa Cruz
    raja@ucolick.org

    A detailed study of the motions of different stellar populations in Andromeda galaxy by UC Santa Cruz scientists using W. M. Keck Observatory data has found striking differences from our own Milky Way, suggesting a more violent history of mergers with smaller galaxies in Andromeda’s recent past. The findings are being presented on Thursday, January 8, at the winter meeting of the American Astronomical Society in Seattle.

    a
    The Andromeda Galaxy
    Adam Evans

    The structure and internal motions of the stellar disk of a spiral galaxy hold important keys to understanding the galaxy’s formation history. The Andromeda galaxy, also called M31, is the closest spiral galaxy to the Milky Way and the largest in the local group of galaxies.

    “In the Andromeda galaxy we have the unique combination of a global yet detailed view of a galaxy similar to our own. We have lots of detail in our own Milky Way, but not the global, external perspective,” said Puragra Guhathakurta, professor of astronomy and astrophysics at the University of California, Santa Cruz.

    The new study, led by UC Santa Cruz graduate student Claire Dorman and Guhathakurta, combined data from two large surveys of stars in Andromeda conducted at the Keck Observatory in Hawaii as well as data from the Hubble Space Telescope.

    NASA Hubble Telescope
    Hubble

    The Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) survey used data from the 10-meter Keck II telescope, fitted with the DEIMOS multi-object spectrograph to measure radial velocities of more than 10,000 individual bright stars in Andromeda.

    Keck DEIMOS
    DEIMOS

    “The sheer light-gathering power of the Keck Observatory, the superb quality of DEIMOS spectra, free of instrumental/atmospheric artifacts, and its ability to obtain spectra of as many as 300 stars at once were crucial to the success of this experiment,” said Guhathakurta. “The Andromeda galaxy is about 2.5 million light years away so even its most luminous stars generally appear quite faint from our vantage point. To measure precise stellar velocities, the white light of each of these faint stars must be subdivided into thousands of wavelengths. The Keck/DEIMOS combination is the only one in the world capable of making these velocity measurements for large numbers of Andromeda stars.”

    The recently completed Panchromatic Hubble Andromeda Treasury (PHAT) survey provided high-resolution imaging at six different wavelengths for more than half of these stars, Dorman said. The study presents the velocity dispersion of young, intermediate-age, and old stars in the disk of Andromeda, the first such measurement in another galaxy.

    Dorman’s analysis revealed a clear trend related to stellar age, with the youngest stars showing relatively ordered rotational motion around the center of the Andromeda galaxy, while older stars displayed much more disordered motion. Stars in a “well ordered” population are all moving coherently, with nearly the same velocity, whereas stars in a disordered population have a wider range of velocities, implying a greater spatial dispersion.

    “If you could look at the disk edge-on, the stars in the well-ordered, coherent population would lie in a very thin plane, whereas the stars in the disordered population would form a much puffier layer,” Dorman explained.

    The researchers considered different scenarios of galactic disk formation and evolution that could account for their observations. One scenario involves the gradual disturbance of a well-ordered disk of stars as a result of mergers with small satellite galaxies. Previous studies have found evidence of such mergers in tidal streams of stars in the extended halo of Andromeda, which appear to be remnants of cannibalized dwarf galaxies. Stars from those galaxies can also accrete onto the disk, but accretion alone cannot account for the observed increase in velocity dispersion with stellar age, Dorman said.

    An alternate scenario involves the formation of the stellar disk from an initially thick, clumpy disk of gas that gradually settled. The oldest stars would then have formed while the gas disk was still in a puffed up and disordered configuration. Over time, the gas disk would have settled into a thinner configuration with more ordered motion, and the youngest stars would then have formed with the disk in that ordered configuration.

    According to Dorman, a combination of these mechanisms could account for the team’s observations. “Our findings should motivate theorists to carry out more detailed computer simulations of these scenarios,” she said.

    The comparison to the Milky Way revealed substantial differences suggesting that Andromeda has had a more violent accretion history in the recent past. “Even the most well ordered Andromeda stars are not as well ordered as the stars in the Milky Way’s disk,” Dorman said.

    In the currently favored “Lambda Cold Dark Matter” paradigm of structure formation in the universe, large galaxies such as Andromeda and the Milky Way are thought to have grown by cannibalizing smaller satellite galaxies and accreting their stars and gas. Cosmologists predict that 70 percent of disks the size of Andromeda’s and the Milky Way’s should have interacted with at least one sizable satellite in the last 10,000 years. The Milky Way’s disk is much too orderly for that to have happened, whereas Andromeda’s disk fits the prediction much better.

    “In this context, the motion of the stars in Andromeda’s disk is more normal, and the Milky Way may simply be an outlier with an unusually quiescent accretion history,” Guhathakurta said.

    Other researchers who collaborated with Dorman and Guhathakurta on this study include Anil Seth at the University of Utah; Daniel Weisz, Julianne Dalcanton, Alexia Lewis, and Benjamin Williams at the University of Washington; Karoline Gilbert at the Space Telescope Science Institute; Evan Skillman at the University of Minnesota; Eric Bell at the University of Michigan; and Katherine Hamren and Elisa Toloba at UC Santa Cruz. This research was funded by the National Science Foundation and NASA.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

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

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

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    Keck Caltech

     
  • richardmitnick 1:29 pm on December 16, 2014 Permalink | Reply
    Tags: , , , , , Keck Observatory   

    From ESO: “Journey to the Centre of the Milky Way Short Fulldome Planetarium Show” 


    European Southern Observatory

    What lies at the heart of our galaxy? For twenty years, ESO’s Very Large Telescope and the Keck telescopes have observed the centre of the Galaxy, looking at the motion of more than a hundred stars and identifying the position of an otherwise invisible object — the supermassive black hole at the centre of our galaxy.

    ESO VLT Interferometer
    ESO VLT Interior
    ESO/VLT

    Keck Observatory
    Keck Observatory Interior
    Keck

    Embark on a Journey to the Centre of the Milky Way and during seven minutes travel faster than light, from the driest place on Earth, the Atacama Desert in Chile right to the centre of our own galaxy, where a black hole is consuming anything that strays into its path. 84 million stars will appear in front of your eyes, each hiding mysteries waiting to be solved. Are there planets around them, perhaps with moons? Do they have water? Could they harbour life?

    Journey to the Centre of the Milky Way is the first fulldome planetarium mini-show produced in-house by ESO for its Planetarium and Visitor Centre, the ESO Supernova, due to open in 2017. Available for free in 4k resolution, the mini-show can be downloaded and used by any planetarium in the world.

    Watch, enjoy, learn.

    See the full article here.

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.

     
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