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  • richardmitnick 3:42 pm on July 30, 2015 Permalink | Reply
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    From Keck: “Telescopes Team Up to Find Distant Uranus-Sized Planet Through Microlensing” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 30, 2015
    SCIENCE CONTACT
    Dave Bennett
    University of Notre Dame
    bennett@nd.edu
    574-315-6621

    Jean-Phillipe Beaulieu
    Institut d’Astrophysique de Paris
    Beaulieu@iap.fr
    +33 6 03 98 73 11

    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808-881-3827

    1
    Credit: NASA, ESA, and A. Feild (STScI)

    The W. M. Keck Observatory in Hawaii and NASA’s Hubble Space Telescope have made independent confirmations of an exoplanet orbiting far from its central star.

    NASA Hubble Telescope
    NASA/ESA Hubble

    The planet was discovered through a technique called gravitational microlensing. This finding opens a new piece of discovery space in the extrasolar planet hunt: to uncover planets as far from their central stars as Jupiter and Saturn are from our sun. The Hubble and Keck Observatory results will appear in two papers in the July 30 edition of The Astrophysical Journal.

    The large majority of exoplanets cataloged so far are very close to their host stars because several current planet-hunting techniques favor finding planets in short-period orbits. But this is not the case with the microlensing technique, which can find more distant and colder planets in long-period orbits that other methods cannot detect.

    Microlensing occurs when a foreground star amplifies the light of a background star that momentarily aligns with it. If the foreground star has planets, then the planets may also amplify the light of the background star, but for a much shorter period of time than their host star. The exact timing and amount of light amplification can reveal clues to the nature of the foreground star and its accompanying planets.

    “Microlensing is currently the only method to detect the planets close to their birth place,” said team member, Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris. “Indeed, planets are being mostly formed at a certain distance from the central star where it is cold enough for volatile compounds to condense into solid ice grains. These grains will then aggregate and will ultimately evolve into planets.”

    The system, cataloged as OGLE-2005-BLG-169, was discovered in 2005 by the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-Up Network (MicroFUN), and members of the Microlensing Observations in Astrophysics (MOA) collaborations—groups that search for extrasolar planets through gravitational microlensing.

    Without conclusively identifying and characterizing the foreground star, however, astronomers have had a difficult time determining the properties of the accompanying planet. Using Hubble and the Keck Observatory, two teams of astronomers have now found that the system consists of a Uranus-sized planet orbiting about 370 million miles from its parent star, slightly less than the distance between Jupiter and the sun. The host star, however, is about 70 percent as massive as our sun.

    “These chance alignments are rare, occurring only about once every 1 million years for a given planet, so it was thought that a very long wait would be required before the planetary microlensing signal could be confirmed,” said David Bennett, the lead of the team that analyzed the Hubble data. “Fortunately, the planetary signal predicts how fast the apparent positions of the background star and planetary host star will separate, and our observations have confirmed this prediction. The Hubble and Keck Observatory data, therefore, provide the first confirmation of a planetary microlensing signal.”

    In fact, microlensing is such a powerful tool that it can uncover planets whose host stars cannot be seen by most telescopes. “It is remarkable that we can detect planets orbiting unseen stars, but we’d really like to know something about the stars that these planets orbit,” explained Virginie Batista, leader of the Keck Observatory analysis. “The Keck and Hubble telescopes allow us to detect these faint planetary host stars and determine their properties.”

    Planets are small and faint compared to their host stars; only a few have been observed directly outside our solar system. Astronomers often rely on two indirect techniques to hunt for extrasolar planets. The first method detects planets by the subtle gravitational tug they give to their host stars. In another method, astronomers watch for small dips in the amount of light from a star as a planet passes in front of it.

    Both of these techniques work best when the planets are either extremely massive or when they orbit very close to their parent stars. In these cases, astronomers can reliably determine their short orbital periods, ranging from hours to days to a couple years.

    But to fully understand the architecture of distant planetary systems, astronomers must map the entire distribution of planets around a star. Astronomers, therefore, need to look farther away from the star—from about the distance of Jupiter is from our sun, and beyond.

    “It’s important to understand how these systems compare with our solar system,” said team member Jay Anderson of the Space Telescope Science Institute in Baltimore, MD. “So we need a complete census of planets in these systems. Gravitational microlensing is critical in helping astronomers gain insights into planetary formation theories.”

    The planet in the OGLE system is probably an example of a “failed-Jupiter” planet, an object that begins to form a Jupiter-like core of rock and ice weighing around 10 Earth masses, but it doesn’t grow fast enough to accrete a significant mass of hydrogen and helium. So it ends up with a mass more than 20 times smaller than that of Jupiter. “Failed-Jupiter planets, like OGLE-2005-BLG-169Lb, are predicted to be more common than Jupiters, especially around stars less massive than the sun, according to the preferred theory of planet formation. So this type of planet is thought to be quite common,” Bennett said.

    Microlensing takes advantage of the random motion of stars, which are generally too small to be noticed without precise measurements. If one star, however, passes nearly precisely in front of a farther background star, the gravity of the foreground star acts like a giant lens, magnifying the light from the background star.

    A planetary companion around the foreground star can produce a variation in the brightening of the background star. This brightening fluctuation can reveal the planet, which can be too faint, in some cases, to be seen by telescopes. The duration of an entire microlensing event is several months, while the variation in brightening due to a planet lasts a few hours to a couple of days.

    The initial microlensing data of OGLE-2005-BLG-169 had indicated a combined system of foreground and background stars plus a planet. But due to the blurring effects of our atmosphere, a number of unrelated stars are also blended with the foreground and background stars in the very crowded star field in the direction of our galaxy’s center.

    “The Hubble Space telescope and KECK2 are unique facilities providing complementary high angular resolution observations to characterise these cold planets orbiting very distant stars,” Beaulieu said.

    The sharp Hubble and Keck Observatory images allowed the research teams to separate out the background source star from its neighbors in the very crowded star field in the direction of our galaxy’s center. Although the Hubble images were taken 6.5 years after the lensing event, the source and lens star were still so close together on the sky that their images merged into what looked like an elongated stellar image.

    Astronomers can measure the brightness of both the source and planetary host stars from the elongated image. When combined with the information from the microlensing light curve, the lens brightness reveals the masses and orbital separation of the planet and its host star, as well as the distance of the planetary system from Earth. The foreground and background stars were observed in several different colors with Hubble’s Wide Field Camera 3 (WFC3), allowing independent confirmations of the mass and distance determinations.

    NASA Hubble WFC3
    WFC3

    The observations, taken with the Near Infrared Camera 2 (NIRC2) on the Keck 2 telescope more than eight years after the microlensing event, provided a precise measurement of the foreground and background stars’ relative motion.

    Keck NIRC2
    NIRC2

    “It is the first time we were able to completely resolve the source star and the lensing star after a microlensing event. This enabled us to discriminate between two models that fit the data of the microlensing light curve,” Batista said.

    The Hubble and Keck Observatory data are providing proof of concept for the primary method of exoplanet detection that will be used by NASA’s planned, space-based Wide-Field Infrared Survey Telescope (WFIRST), which will allow astronomers to determine the masses of planets found with microlensing.

    NASA WFIRST telescope
    WFIRST

    WFIRST will have Hubble’s sharpness to search for exoplanets using the microlensing technique. The telescope will be able to observe foreground, planetary host stars approaching the background source stars prior to the microlensing events, and receding from the background source stars after the microlensing events.

    “WFIRST will make measurements like we have made for OGLE-2005-BLG-169 for virtually all the planetary microlensing events it observes. We’ll know the masses and distances for the thousands of planets discovered by WFIRST,” Bennett explained.

    See the full article here.

    Please help promote STEM in your local schools.

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    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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  • richardmitnick 3:16 pm on July 30, 2015 Permalink | Reply
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    From Keck: “Keck Observatory Names Chief Scientist” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 30, 2015
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808-881-3827

    1
    Anne L Kinney, Credit: NASA

    W. M. Keck Observatory is very pleased to announce Anne Kinney has been appointed Chief Scientist, effective August 3, 2015.

    “We are delighted to welcome Anne as the Chief Scientist of Keck Observatory,” said observatory Director, Hilton Lewis. “In this new role, she will be responsible for stewardship of the observatory’s scientific programs and for ensuring the health and vibrancy of the science conducted at this observatory.”

    Kinney comes to Keck Observatory from NASA, where she was most recently the Director of the Solar System Exploration Division at Goddard Space Flight Center. Kinney brings more than 30 years of scientific research and organizational leadership experience. She holds a PhD from New York University in Physics and Astronomy and is very familiar with Keck Observatory as she has been a member of the observatory’s Science Steering Committee since 2012.

    “It is my great pleasure to be joining the stellar Keck Observatory team,” Kinney said. “For me, one of the great attractions is the quality and dedication of its team. Keck Observatory’s international reputation speaks to the remarkable focus that the staff brings to extracting peak performance from two telescopes that are as beautiful as they are cutting edge.”

    Prior to her service at Goddard, Kinney was the Director of the Universe Division in the Science Mission Directorate at NASA Headquarters, with a portfolio including Hubble Space Telescope, Chandra X-ray Observatory, Spitzer Space Telescope, SOFIA, and Fermi.

    Kinney is an expert in extragalactic astronomy and has published 80 papers in refereed journals on quasars, blazars, active galaxies and normal galaxies, and signatures of accretion disks in active galaxies. She has demonstrated that accretion disks in the center of active galaxies lie at random angles relative to their host galaxies.

    Kinney received the Presidential Rank Award in 2012, has received two Exceptional Leadership Awards at NASA, and was a visiting scholar at the Institute of Astronomy in Cambridge.

    “I am thrilled that Anne has agreed to join us and contribute her energy and expertise to advance WMKO’s leadership in ground-based astronomy,” Lewis said.

    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 4:16 pm on July 27, 2015 Permalink | Reply
    Tags: , , Keck Observatory, SLUGGS Survey   

    From Keck: “Fossil Star Clusters Reveal Their Age” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 27, 2015

    1
    Cosmic timeline showing the birth of the Universe in a Big Bang 13.7 billion years ago to the present day. Using the Keck Observatory, an international team of researchers led by Professor Forbes of Swinburne University of Technology has determined ancient star clusters, known as globular clusters, formed in two epochs – 12.5 and 11.5 billion years ago. They formed alongside galaxies, rather than prior to galaxies, as previously thought. Credit: NASA/CXC/SAO and A. Romanowsky.

    Using a new age-dating method and the W. M. Keck Observatory on Maunakea, an international team of astronomers have determined that ancient star clusters formed in two distinct epochs – the first 12.5 billion years ago and the second 11.5 billion years ago. These results are being published in Monthly Notices of the Royal Astronomical Society.

    Although the clusters are almost as old as the Universe itself, these age measurements show the star clusters – called globular clusters – are actually slightly younger than previously thought.

    “We now think that globular clusters formed alongside galaxies rather than significantly before them,” research team leader, Professor Duncan Forbes of Swinburne University of Technology said.

    The new estimates of the star cluster average ages were made possible using data obtained from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, which was carried out on Keck Observatory’s 10-meter, Keck II telescope. Observations were carried out over years using the powerful DEIMOS multi-object spectrograph fitted on Keck II, which is capable of obtaining spectra of one hundred globular clusters in a single exposure.

    Keck DEIMOS
    DEIMOS

    DEIMOS breaks the visible wavelengths of objects into spectra, which the team used to reverse-engineer the ages of the globular clusters by comparing the chemical composition of the globular clusters with the chemical composition of the Universe as it changes with time.

    “The Universe is now well known to be 13.7 billion years old,” research team member and Professor Jean Brodie said. “We determined globular clusters form on average some 1.2 and 2.2 billion years after the Big Bang.”

    “Our age measurements indicate that globular clusters managed to avoid the period, called cosmic re-ionization, in which the Universe was bathed in ultra-violet radiation which could have destroyed them” said fellow team member, Professor Aaron Romanowsky.

    “Now that we have estimated when globular clusters form, we next need to tackle the questions of where and how they formed.” Forbes said.

    The SLUGGS survey is comprised of an international team of astronomers who aim to understand the formation and evolution of galaxies and their globular cluster systems.

    Globular clusters are tightly bound clusters of around a million stars. Most large galaxies, including the Milky Way, host a system of globular clusters. Although the Universe itself, and galaxies within it, has evolved over cosmic time, globular clusters are very robust and many have survived intact for over 10 billion years.

    The team of astronomers includes researchers and PhD students from Swinburne University of Technology (Australia), University of California at Santa Cruz (USA), San Jose State University (USA).

    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 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 6:43 am on July 24, 2015 Permalink | Reply
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    From Keck: “Found: Earth’s Closest Cousin Yet” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 23, 2015
    No Writer Credit

    1
    This artist’s concept compares Earth (left) to the new planet, called Kepler-452b, which is about 60 percent larger in diameter.
    Credit: NASA/JPL-Caltech/T. Pyle

    2
    This size and scale of the Kepler-452 system compared alongside the Kepler-186 system and the solar system. Kepler-186 is a miniature solar system that would fit entirely inside the orbit of Mercury. Credit: NASA/JPL-CalTech/R. Hurt

    The W. M. Keck Observatory has confirmed the first near-Earth-size planet in the “habitable zone” around a sun-like star. This discovery and the introduction of 11 other new small habitable zone candidate planets were originally made by NASA’s Kepler space telescopes and mark another milestone in the journey to finding another “Earth.”

    NASA Kepler Telescope
    Kepler

    “We can think of Kepler-452b as bigger, older cousin to Earth, providing an opportunity to understand and reflect upon Earth’s evolving environment,” said Jon Jenkins, Kepler data analysis lead at NASA’s Ames Research Center in Moffett Field, California, who led the team that discovered Kepler-452b. “It’s awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star; about 1.5 billion years longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet.”

    The data from Kepler suggested to the team there was a planet causing the light from it’s host star to dim as is orbited around it. The team then turned to ground-based observatories including the University of Texas at Austin’s McDonald Observatory, the Fred Lawrence Whipple Observatory on Mt. Hopkins, Arizona, and the world’s largest telescopes at Keck Observatory on Maunakea, Hawaii for confirmation.

    U Texas McDonald Observatory Campus
    University of Texas at Austin’s McDonald Observatory

    CfA Whipple Observatory
    CfA Fred Lawrence Whipple Observatory

    Specifically, the ten-meter Keck I telescope, fitted with the HIRES instrument was used to confirm the Kepler data as well as to more precisely determine the properties of the star, specifically its temperature, surface gravity and metallicity.

    Keck HIRES
    HIRES

    “These fundamental properties are used to determine the stellar mass and radius allowing for precise determination of the planet size,” said Howard Isaacson, researcher in the astronomy department at UC Berkeley and mamba of the discovery team. “With the precise stellar parameters from the HIRES spectrum, we can show that planet radius is closer to the size of the Earth, than say Neptune (~4x Earth’s radius). With a radius of 1.6 times the radius of the Earth, the chances of the planet having some sort of rocky surface is predicted to be ~50%. The Keck Observatory spectrum is also used to rule out false positive scenarios. Background stars can confuses the interpretation of the planet hypothesis, and the Keck Observatory spectrum shows that no such background stars are present.”

    The newly discovered Kepler-452b is the smallest planet to date discovered orbiting a sun-like star (G2-type star) in the habitable zone — the area around a star where liquid water could pool on the surface of an orbiting planet. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030.

    Kepler-452b is 60 percent larger than Earth and is considered a super-Earth-size planet. While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a good chance of being rocky.

    While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than Earth is from the Sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 10 percent larger and 20 percent brighter.

    The Kepler-452 system is located 1,400 light-years away in the constellation Cygnus. The research paper reporting this finding has been accepted for publication in The Astronomical Journal.

    In addition to confirming Kepler-452b, the Kepler team has increased the number of new exoplanet candidates by 521 from their analysis of observations conducted from May 2009 to May 2013, raising the number of planet candidates detected by the Kepler mission to 4,696. Candidates require follow-up observations and analysis to verify they are actual planets.

    Twelve of the new planet candidates have diameters between one to two times that of Earth, and orbit in their star’s habitable zone. Of these, nine orbit stars that are similar to our sun in size and temperature. These candidates are likely targets for future observing runs at Keck Observatory for confirmation.

    “We’ve been able to fully automate our process of identifying planet candidates, which means we can finally assess every transit signal in the entire Kepler dataset quickly and uniformly,” said Jeff Coughlin, Kepler scientist at the SETI Institute in Mountain View, California, who led the analysis of a new candidate catalog. “This gives astronomers a statistically sound population of planet candidates to accurately determine the number of small, possibly rocky planets like Earth in our Milky Way galaxy.”

    These findings, presented in the seventh Kepler Candidate Catalog, will be submitted for publication in the Astrophysical Journal. These findings are derived from data publically available on the NASA Exoplanet Archive.

    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 3:12 pm on July 10, 2015 Permalink | Reply
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    Keck’s Take on the Black Hole in CID-947″ 

    Keck Observatory

    Keck Observatory

    The subject was previously covered in an earlier post, “From Chandra: ‘A Precocious Black Hole'”. But the writers at Keck spent a lot of time on this, and their views are always excellent, so it is worth seeing their work.

    Keck Observatory

    “Gigantic, Early Black Hole Could Upend Evolutionary Theory”

    July 9, 2015

    SCIENCE CONTACT
    Benny Trakhtenbrot
    ETH Zürich
    Institute for Astronomy, Switzerland
    benny.trakhtenbrot@phys.ethz.ch
    +41 (0)44-632-4213

    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808-881-3827

    1
    In this illustration a black hole emits part of the accreted matter in the form of energetic radiation (blue), without slowing down star formation within the host galaxy (purple regions). Credit: M. Helfenbein, Yale University / OPAC

    An international team of astrophysicists led by Benny Trakhtenbrot, a researcher at ETH Zurich’s Institute for Astronomy, discovered a gigantic black hole in an otherwise normal galaxy, using W. M. Keck Observatory’s 10-meter, Keck I telescope in Hawaii. The team, conducting a fairly routine hunt for ancient, massive black holes, was surprised to find one with a mass of more than 7 billion times our Sun making it among the most massive black holes ever discovered. And because the galaxy it was discovered in was fairly typical in size, the study calls into question previous assumptions on the development of galaxies. Their findings are being published today in the journal Science.

    The data, collected with Keck Observatory’s newest instrument called MOSFIRE, revealed a giant black hole in a galaxy called CID-947 that was 11 billion light years away.

    Keck MOSFIRE
    MOSFIRE

    The incredible sensitivity of MOSFIRE coupled to the world’s largest optical/infrared telescope meant the scientists were able to observe and characterize this black hole as it was when the Universe was less than two billion years old, just 14 percent of its current age (almost 14 billion years have passed since the Big Bang).

    Even more surprising than the black hole’s record mass, was the relatively ordinary mass of the galaxy that contained it.

    Most galaxies host black holes with with masses less than one percent of the galaxy. In CID-947, the black hole mass is 10 percent that of its host galaxy. Because of this remarkable disparity, the team deduced this black hole grew so quickly the host galaxy was not able to keep pace, calling into question previous thinking on the co-evolution of galaxies and their central black holes.

    “The measurements of CID-947 correspond to the mass of a typical galaxy,” Trakhtenbrot said. “We therefore have a gigantic black hole within a normal size galaxy. The result was so surprising, two of the astronomers had to verify the galaxy mass independently. Both came to the same conclusion.”

    “Black holes are objects that possess such a strong gravitational force that nothing – not even light – can escape,” said Professor Meg Urry of Yale University, co-author of the study. ” Einstein’s theory of relativity describes how they bend space-time itself. The existence of black holes can be proven because matter is greatly accelerated by the gravitational force and thus emits particularly high-energy radiation.”

    Until now, observations have indicated that the greater the number of stars present in the host galaxy, the bigger the black hole. “This is true for the local Universe, which merely reflects the situation in the Universe’s recent past,” Urry said.

    Furthermore, previous studies suggest the radiation emitted during the growth of the black hole controlled, or even stopped, the creation of stars as the released energy heated up the gas. This cumulative evidence led scientists to assume the growth of black holes and the formation of stars go hand-in-hand.

    The latest results, however, suggest that these processes work differently, at least in the early Universe.

    The distant young black hole observed by Trakhtenbrot, Urry and their colleagues had roughly 10 times less mass than its galaxy. In today’s local Universe, black holes typically reach a mass of 0.2 to 0.5 percent of their host galaxy’s mass. “That means this black hole grew much more efficiently than its galaxy – contradicting the models that predicted a hand-in-hand development,” he said.

    The researchers also concluded stars were still forming even though the black hole had reached the end of its growth. Contrary to previous assumptions, the energy and gas flow propelled by the black hole did not stop the creation of stars.

    “From the available Chandra data for the source, we also concluded that the black hole has a very low accretion rate, and is therefore reached the end of its growth. On the other had, other data suggests that stars were still forming throughout the host galaxy,” Trakhtenbrot said.

    NASA Chandra Telescope
    NASA/Chandra

    The galaxy could continue to grow in the future, but the relationship between the mass of the black hole and that of the stars would remain unusually large. The researchers believe CID-947 could be a precursor of the most extreme, massive systems that we observe in today’s local Universe, such as the galaxy NGC 1277 in the constellation of Perseus, some 220 million light years away from our Milky Way.

    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.

    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 2:59 pm on June 2, 2015 Permalink | Reply
    Tags: , , Keck Observatory, Superclusters   

    From Keck: “Laniakea: Our home supercluster” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    Superclusters – regions of space that are densely packed with galaxies – are the biggest structures in the Universe. But scientists have struggled to define exactly where one supercluster ends and another begins. Now, a team based in Hawaii has come up with a new technique that maps the Universe according to the flow of galaxies across space. Redrawing the boundaries of the cosmic map, they redefine our home supercluster and name it Laniakea, which means ‘immeasurable heaven’ in Hawaiian.

    Watch, enjoy, learn.

    Temp 0

    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 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
    Tags: , , Keck Observatory,   

    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.

    STEM Icon

    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

     
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