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  • richardmitnick 1:57 pm on August 25, 2016 Permalink | Reply
    Tags: , , Dark galaxy Dragonfly 44, , , , Keck Observatory   

    From Keck: “Scientists Discover Massive Galaxy Made of 99.99 Percent Dark Matter” 

    Keck Observatory

    August 25, 2016

    SCIENCE CONTACT
    Pieter van Dokkum
    Yale University
    New Haven, Connecticut, USA
    Tel: +1-203-432-3000
    E-mail: pieter.vandokkum@yale.edu

    MEDIA CONTACT

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

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    1
    The dark galaxy Dragonfly 44. The image on the left is a wide view of the galaxy taken with the Gemini North telescope using the Gemini Multi-Object Spectrograph (GMOS). The close-up on the right is from the same very deep image, revealing the large, elongated galaxy, and halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way Galaxy. Dragonfly 44 is very faint for its mass, and consists almost entirely of Dark Matter. Credit: Pieter van Dokkum, Roberto Abraham, Gemini; Sloan Digital Sky Survey.

    Using the world’s most powerful telescopes, an international team of astronomers has discovered a massive galaxy that consists almost entirely of Dark Matter. Using the W. M. Keck Observatory and the Gemini North telescope – both on Maunakea, Hawaii – the team found a galaxy whose mass is almost entirely Dark Matter. The findings are being published in The Astrophysical Journal Letters today.

    Gemini/North telescope at Manua Kea, Hawaii, USA
    GEMINI/North GMOS
    Gemini/North telescope at Manua Kea, Hawaii, USA; GEMINI/North GMOS

    Even though it is relatively nearby, the galaxy, named Dragonfly 44, had been missed by astronomers for decades because it is very dim. It was discovered just last year when the Dragonfly Telephoto Array observed a region of the sky in the constellation Coma.

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

    Upon further scrutiny, the team realized the galaxy had to have more than meets the eye: it has so few stars that it quickly would be ripped apart unless something was holding it together.

    To determine the amount of Dark Matter in Dragonfly 44, astronomers used the DEIMOS instrument installed on Keck II to measure the velocities of stars for 33.5 hours over a period of six nights so they could determine the galaxy’s mass.

    Keck/DEIMOS
    Keck/DEIMOS

    The team then used the Gemini Multi-Object Spectrograph (GMOS) on the 8-meter Gemini North telescope on Maunakea in Hawaii to reveal a halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way Galaxy.

    “Motions of the stars tell you how much matter there is, van Dokkum said. “They don’t care what form the matter is, they just tell you that it’s there. In the Dragonfly galaxy stars move very fast. So there was a huge discrepancy: using Keck Observatory, we found many times more mass indicated by the motions of the stars, then there is mass in the stars themselves.”

    The mass of the galaxy is estimated to be a trillion times the mass of the Sun – very similar to the mass of our own Milky Way galaxy. However, only one hundredth of one percent of that is in the form of stars and “normal” matter; the other 99.99 percent is in the form of dark matter. The Milky Way has more than a hundred times more stars than Dragonfly 44.

    Finding a galaxy with the mass of the Milky Way that is almost entirely dark was unexpected. “We have no idea how galaxies like Dragonfly 44 could have formed,” Roberto Abraham, a co-author of the study, said. “The Gemini data show that a relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue. But at the moment we’re just guessing.”

    “This has big implications for the study of Dark Matter,” van Dokkum said. “It helps to have objects that are almost entirely made of Dark Matter so we don’t get confused by stars and all the other things that galaxies have. The only such galaxies we had to study before were tiny. This finding opens up a whole new class of massive objects that we can study.

    “Ultimately what we really want to learn is what Dark Matter is,” van Dokkum said. “The race is on to find massive dark galaxies that are even closer to us than Dragonfly 44, so we can look for feeble signals that may reveal a Dark Matter particle.”

    Additional co-authors are Shany Danieli, Allison Merritt, and Lamiya Mowla of Yale, Jean Brodie of the University of California Observatories, Charlie Conroy of Harvard, Aaron Romanowsky of San Jose State University, and Jielai Zhang of the University of Toronto.

    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 Maunakea 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 (DEep Imaging Multi-Object Spetrograph) boasts the largest field of view (16.7 arcmin by 5 arcmin) of any of the Keck Observatory 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 3:50 pm on August 24, 2016 Permalink | Reply
    Tags: , , Keck Observatory, Most Distant Galaxy Clusters Ever Found   

    From Keck: “Most Distant Galaxy Clusters Ever Found” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    August 24, 2016
    Steve Jefferson
    W. M. Keck Observatory
    (808) 881-3827
    sjefferson@keck.hawaii.edu

    1
    Massive galaxy cluster MACS J0416 seen in X-rays (blue), visible light (red, green, and blue), and radio light (pink). Credit: NASA/CXC/SAO/G.Ogrean/STScI/NRAO/AUI/NSF.

    2
    Color images of the central regions of z > 1.35 SpARCS clusters. Cluster members are marked with white squares. Credit: Nantais, et al.

    The international University of California, Riverside-led SpARCS collaboration has discovered four of the most distant clusters of galaxies ever found, as they appeared when the Universe was only four billion years old. Clusters are rare regions of the Universe consisting of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious Dark Matter. Spectroscopic observations from the W. M. Keck Observatory on Maunakea, Hawaii and the Very Large Telescope in Chile confirmed the four candidates to be massive clusters.

    ESO/VLT at Cerro Paranal, Chile
    ESO/VLT at Cerro Paranal, Chile

    This sample is now providing the best measurement yet of when and how fast galaxy clusters stop forming stars in the early Universe.

    “We looked at how the properties of galaxies in these clusters differed from galaxies found in more typical environments with fewer close neighbors,” said lead author Julie Nantais, an assistant professor at the Andres Bello University in Chile. “It has long been known that when a galaxy falls into a cluster, interactions with other cluster galaxies and with hot gas accelerate the shut off of its star formation relative to that of a similar galaxy in the field, in a process known as environmental quenching. The SpARCS team have developed new techniques using Spitzer Space Telescope infrared observations to identify hundreds of previously-undiscovered clusters of galaxies in the distant Universe.”

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    As anticipated, the team did indeed find that many more galaxies in the clusters had stopped forming stars compared to galaxies of the same mass in the field. Gillian Wilson, professor of physics and astronomy at UC Riverside, added, “Fascinatingly, however, the study found that the percentage of galaxies which had stopped forming stars in those young, distant clusters, was much lower than the percentage found in much older, nearby clusters. While it had been fully expected that the percentage of cluster galaxies which had stopped forming stars would increase as the Universe aged, this latest work quantifies the effect.”

    The paper concludes that about 30 percent of the galaxies which would normally be forming stars have been quenched in the distant clusters, compared to the much higher value of about 50 percent found in nearby clusters.

    Several possible physical processes could be responsible for causing environmental quenching. For example, the hot, harsh cluster environment might prevent the galaxy from continuing to accrete cold gas and form new stars; a process astronomers have named “starvation”. Alternatively, the quenching could be caused by interactions with other galaxies in the cluster. These galaxies might “harass” (undergo frequent, high speed, gravitationally-disturbing encounters), tidally strip (pull material from a smaller galaxy to a larger one) or merge (two or more galaxies joining together) with the first galaxy to stop its star formation.

    While the current study does not answer the question of which process is primarily responsible, it is nonetheless hugely important because it provides the most accurate measurement yet of how much environmental quenching has occurred in the early Universe. Moreover, the study provides an all-important early-Universe benchmark by which to judge upcoming predictions from competing computational numerical simulations which make different assumptions about the relative importance of the many different environmental quenching processes which have been suggested, and the timescales upon which they operate.

    The W. M. Keck Observatory findings were obtained as the result of a collaboration amongst UC faculty members Gillian Wilson (UCR) and Michael Cooper (UCI), and graduate students Andrew DeGroot (UCR) and Ryan Foltz (UCR). Other authors involved in the study are Remco van der Burg (Université Paris Diderot), Chris Lidman (Australian Astronomical Observatory), Ricardo Demarco (WUniversidad de Concepción, Chile), Allison Noble (University of Toronto, Canada) and Adam Muzzin (University of Cambridge).

    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

    Science paper:
    Stellar mass function of cluster galaxies at z ~ 1.5: evidence for reduced quenching efficiency at high redshift, Astronomy and Astrophysics, 24 August 2016

    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 1:39 pm on August 3, 2016 Permalink | Reply
    Tags: , Keck Observatory, MOSFIRE on Keck 1, UCLA Astronomers Use Keck Observatory to Look Back 12 Billion Years and Measure Oxygen   

    From Keck: “UCLA Astronomers Use Keck Observatory to Look Back 12 Billion Years and Measure Oxygen” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    August 3, 2016
    Steve Jefferson
    W. M. Keck Observatory
    (808) 881-3827
    sjefferson@keck.hawaii.edu

    UCLA astronomers have used the W. M. Keck Observatory on Maunakea, Hawaii to make the first accurate measurement of the abundance of oxygen in a distant galaxy. Oxygen, the third-most abundant chemical element in the Universe, is created inside stars and released into interstellar gas when stars die. Quantifying the amount of oxygen is key to understanding how matter cycles in and out of galaxies. This research is published online in the Astrophysical Journal Letters.

    1
    Galaxy COSMOS-1908 is in the center of this Hubble Space Telescope image, indicated by the arrow. Nearly everything in the image is a galaxy. Credit: Ryan Sanders and the CANDELS team

    “This is by far the most distant galaxy for which the oxygen abundance has actually been measured,” said Alice Shapley, a UCLA professor of astronomy, and co-author of the study. “We’re looking back in time at this galaxy as it appeared 12 billion years ago.”

    Knowing the abundance of oxygen in the galaxy called COSMOS-1908 is an important stepping stone toward allowing astronomers to better understand the population of faint, distant galaxies observed when the Universe was only a few billion years old, Shapley said.

    COSMOS-1908 contains approximately one billion stars. In contrast, the Milky Way contains approximately 100 billion stars. Furthermore, COSMOS-1908 contains approximately only 20 percent the abundance of oxygen that is observed in the Sun.

    Typically, astronomers rely on extremely indirect and imprecise techniques for estimating oxygen abundance for the vast majority of distant galaxies. But in this case, UCLA researchers used a direct measurement, said Ryan Sanders, astronomy graduate student and the study’s lead author.

    “Close galaxies are much brighter, and we have a very good method of determining the amount of oxygen in nearby galaxies,” Sanders said.

    In faint, distant galaxies, the task is dramatically more difficult, but COSMOS-1908 was one case for which Sanders was able to apply the “robust” method commonly applied to nearby galaxies. “We hope this will be the first of many,” he said.

    Shapley said that prior to Sanders’ discovery, researchers didn’t know if they could measure how much oxygen there was in these distant galaxies.

    “Ryan’s discovery shows we can measure the oxygen and compare these observations with models of how galaxies form and what their history of star formation is,” Shapley said.

    The researchers used an extremely advanced and sophisticated instrument called MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration) installed on the Keck I telescope at the Keck Observatory.

    Keck/MOSFIRE on Keck 1, Mauna Kea, Hawaii, USA
    Keck/MOSFIRE on Keck 1, Mauna Kea, Hawaii, USA

    This five-ton instrument was designed to study the most distant, faintest galaxies, said UCLA physics and astronomy professor Ian McLean, co-project leader on MOSFIRE and director of UCLA’s Infrared Laboratory for Astrophysics. McLean and co-principal investigator Chuck Steidel from the California Institute of Technology built the instrument with colleagues colleagues from UCLA, Caltech, UC Santa Cruz and industrial sub-contractors.

    The amount of oxygen in a galaxy is determined primarily by three factors: how much oxygen comes from large stars that end their lives violently in supernova explosions — a ubiquitous phenomenon in the early Universe, when the rate of stellar births was dramatically higher than the rate in the Universe today; how much of that oxygen gets ejected from the galaxy by so-called “super winds,” which propel oxygen and other interstellar gases out of galaxies at hundreds of thousands of miles per hour; and how much pristine gas enters the galaxy from the intergalactic medium, which doesn’t contain much oxygen.

    “If we can measure how much oxygen is in a galaxy, it will tell us about all these processes,” said Shapley, who, along with Sanders, is interested in learning how galaxies form and evolve, why galaxies have different structures, and how galaxies exchange material with their intergalactic environments.

    Shapley expects the measurements of oxygen will reveal that super winds are very important in how galaxies evolved. “Measuring the oxygen content of galaxies over cosmic time is one of the key methods we have for understanding how galaxies grow, as well as how they spew out gas into the intergalactic medium,” she said.

    Keck Observatory’s MOSFIRE collects visible-light photons from objects billions of light years away whose wavelengths have been stretched or “redshifted” to the infrared by the expansion of the Universe. Due to the finite speed of light, MOSFIRE is providing a view of these galaxies as they existed billions of years ago, when the light first started traveling to Earth. MOSFIRE is a type of instrument known as a “spectrograph,” which spreads the light from astronomical objects out into a spectrum of separate wavelengths (colors), indicating the specific amount of energy emitted at each wavelength. Spectrographs enable astronomers to determine the chemical contents of galaxies, because different chemical elements — such as oxygen, carbon, iron or hydrogen — each provide a unique spectral fingerprint, emitting light at specific wavelengths.

    To characterize the chemical contents of COSMOS-1908, Sanders analyzed a particular wavelength in the MOSFIRE spectrum of this galaxy that is sensitive to the amount of oxygen. “It’s an amazing instrument, which made Ryan’s measurement possible,” Shapley said.

    Data for COSMOS-1908 were collected as part of the MOSFIRE Deep Evolution Field (MOSDEF) survey, a large Keck Observatory project that Shapley and Sanders have carried out in collaboration with astronomers at UC Berkeley, UC Riverside and UCSD. Between 2012 and 2016, the MOSDEF survey was allocated roughly 50 nights of MOSFIRE time on the Keck I telescope to study distant galaxies forming in the early Universe.

    The research was funded by both the National Science Foundation and NASA. MOSFIRE was also funded by the National Science Foundation (through the Telescope System Instrumentation program), and by 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 4:03 pm on July 18, 2016 Permalink | Reply
    Tags: , , Four Synchronized Planets Reveal Clues to How Planets Form, Keck Observatory   

    From Keck: “Four Synchronized Planets Reveal Clues to How Planets Form” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    May 11, 2016 [Just now in social media]
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu

    1
    The Kepler–223 planetary system. Credit: W. Rebel

    The search for planets orbiting other stars in our galaxy has revealed an extraordinary family of planets whose orbits are so carefully timed that they provide long-term stability for their planetary system. The data came from observations from the Kepler Space Telescope and the W. M. Keck Observatory on Maunakea, Hawaii. A paper describing the formation of this planetary system by a research team was published in the journal Nature today.

    “The Kepler-223 planetary system has unusually long-term stability because its four planets interact gravitationally to keep the beat of a carefully choreographed dance as they orbit their host star,” said Eric Ford, a professor of astronomy and astrophysics at Penn State and a member of the research team. Each time the innermost planet (Kepler-223b) orbits the system’s star 3 times, the second-closest planet (Kepler-223c) orbits precisely 4 times. Thus, these two planets return to the same positions relative to each other and their host star.

    Throughout the Kepler-233 system, the dance is much more elaborate. “The orbital periods of the four planets of the Kepler-233 system have ratios of exactly 3 to 4, 4 to 6, and 6 to 8,” Ford said. The ratio of the orbits of the four planets is so precise that they provide a stabilizing influence for the planetary system. “The precisely timed orbits of these planets places strong constraints on how they could have formed,” Ford said.

    “Our analysis shows that a slow, smooth, migration of the system during its formation and evolution would be able to place these planets into the delicately balanced configuration that we observe today,” Ford said. An example closer to home on Earth is the synchronization that a side-by-side group of undisturbed mechanical metronomes achieve over time, even though they each begin ticking at a different frequency [https://www.youtube.com/watch?v=tlYIyKic3w8]. “The Kepler-223 system is one of the best examples of a system that provides such strong clues about how its planets could have formed,” Ford said.

    Studying systems like Kepler-223 is important because they provide a rare opportunity to test models of planet formation. Ford said that the research team’s results have implications for many other planetary systems. The team performed numerical simulations of planetary migration that generated the Kepler-223 system’s current architecture, which is similar to the migration suspected for planets of our outer solar system, Jupiter, Saturn, Uranus, and Neptune. “Kepler found lots of systems with multiple super-Earth and/or sub-Neptune-size planets orbiting close to their host star, but the vast majority of these systems are not in a special resonant configuration like that of Kepler-223,” Ford said. “Many of these systems may have formed similarly to Kepler-223, but then later became destabilized, perhaps by a more distant massive planet or perhaps by the cumulative effect of the scattering of many smaller planetesimals left over from the planet-building process.”

    The scientists used data from NASA’s Kepler telescope to measure how much starlight each of the four planets block as they pass in front of their star, and to detect slight changes in each of the planets’ orbits. Combining observations from Kepler and the Keck Observatory, the team was able to infer the planets’ sizes and masses.

    Ford’s contributions to the research included improving the computational efficiency and quality of the statistical analysis, which enabled the team to provide statistically rigorous constraints on the planets’ masses and orbits. “Often, advanced statistical and dynamical modeling is required to account for the rich array of astrophysical effects detected by the Kepler observatory. For systems with strongly interacting planets, like Kepler-223, such analyzes require a combination of efficient statistical algorithms and significant computing resources,” Ford said.

    “Several faculty, postdoctoral researchers, and students at Penn State’s Center for Exoplanets and Habitable Worlds are actively engaged in performing detailed analyzes of the rich treasure trove of data from Kepler’s most exciting discoveries, such as Kepler-223,” Ford said. At Penn State, researchers associated with the Center for Astrostatistics and the Institute for Cyberscience are leaders in developing and applying advanced statistical and computational methods that are important for this and other data resulting from science research. Penn State’s new interdisciplinary Statistical Modeling Data Science program is beginning to train undergraduates to apply the theoretical machinery of modern statistics to the search for answers to questions involving very complex or massive amounts of data — known as “big data.”

    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 4:52 pm on June 2, 2016 Permalink | Reply
    Tags: , Keck Observatory, Universe’s Expansion is Faster Than Expected   

    From Keck: “Universe’s Expansion is Faster Than Expected” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    There are NASA and ESA articles on this same finding. The references to those articles are below.

    June 2, 2016
    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    (808) 881-3827
    sjefferson@keck.hawaii.edu

    SCIENCE CONTACT
    Alex Filippenko
    (510) 852-4829
    afilippenko@berkeley.edu

    1
    An image of the galaxy UGC 9391, one of the galaxies in the new survey. UGC 9391 contains the two types of stars – Cepheid variables and a Type 1a supernova – that astronomers used to calculate a more precise Hubble constant. The red circles that mark the locations of Cepheids. The blue “X” denotes the location of supernova 2003du, a Type Ia supernova. Credit: NASA, ESA, and A. Riess [STScI/JHU])

    Astronomers using the W. M. Keck Observatory on Maunakea, Hawaii have obtained the most precise measurement yet of how fast the universe is expanding at the present time, and it doesn’t agree with predictions based on other data and our current understanding of the physics of the cosmos. The discrepancy – the universe is now expanding 9 percent faster than expected — means either that measurements of the cosmic microwave background radiation are wrong, or that some unknown physical phenomenon is speeding up the expansion of space, the astronomers say. The results*, using data from Keck Observatory and the Hubble Space Telescope, will appear in an upcoming issue of The Astrophysical Journal.

    “If you really believe our number – and we have shed blood, sweat and tears to get our measurement right and to accurately understand the uncertainties – then it leads to the conclusion that there is a problem with predictions based on measurements of the cosmic microwave background radiation, the leftover glow from the Big Bang,” said Alex Filippenko, a UC Berkeley professor of astronomy and co-author of a paper announcing the discovery.

    Using the Keck-I 10-meter telescope in Hawaii, Filippenko’s group measured the chemical abundances of gases near the locations of Cepheid variable stars in the nearby galaxies hosting Type Ia supernovae. This allowed them to improve the accuracy of the derived distances of these galaxies, and thus to more accurately calibrate the peak luminosities of their Type Ia supernovae.

    “We’ve done the world’s best job of decreasing the uncertainty in the measured rate of universal expansion and of accurately assessing the size of this uncertainty,” said Filippenko, “yet we find that our measured rate of expansion is probably incompatible with the rate expected from observations of the young universe, suggesting that there’s something important missing in our physical understanding of the universe.”

    “Maybe the universe is tricking us, or our understanding of the universe isn’t complete,” he said.

    The cause could be the existence of another, unknown particle – perhaps an often-hypothesized fourth flavor of neutrino – or that the influence of dark energy (which accelerates the expansion of the universe) has increased over the 13.8 billion year history of the universe. Or perhaps Einstein’s general theory of relativity, the basis for the Standard Model, is slightly wrong.

    “This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 percent of everything and don’t emit light, such as dark energy, dark matter and dark radiation,” said Nobel Laureate Adam Riess, the leader of the study from the Space Telescope Science Institute and The Johns Hopkins University, both in Baltimore, Maryland. Riess is a former UC Berkeley post-doctoral fellow who worked with Filippenko.

    Afterglow of Big Bang

    A few years ago, the European Space Agency’s Planck observatory – now out of commission – measured fluctuations in the cosmic background radiation to document the universe’s early history. Planck’s measurements, combined with the current Standard Model of physics, predicted an expansion rate today of 66.53 (±0.62) kilometers per second per megaparsec. A megaparsec equals 3.26 million light-years.

    Previous direct measurements of galaxies pegged the current expansion rate, or Hubble constant, between 70 and 75 km/sec/Mpc, give or take about 5-10 percent – a result that is not definitely in conflict with the Planck predictions. But the new direct measurements yield a rate of 73.24 (±1.74) km/sec/Mpc, an uncertainty of only 2.4 percent, and clearly incompatible with the Planck predictions, Filippenko said.

    The team, several of whom were part of the High-z Supernova Search Team that co-discovered the accelerating expansion of the universe in 1998, refined the universe’s current expansion rate by developing innovative techniques that improved the precision of distance measurements to faraway galaxies.

    The team looked for galaxies containing both a type of variable star called a Cepheid and Type Ia supernovae. Cepheid stars pulsate at rates that correspond to their true brightness (power), which can be compared with their apparent brightness as seen from Earth to accurately determine their distance and thus the distance of the galaxy. Type Ia supernovae, another commonly used cosmic yardstick, are exploding stars that flare with the same intrinsic brightness and are brilliant enough to be seen from much longer distances.

    By measuring about 2,400 Cepheid stars in 19 nearby galaxies and comparing the apparent brightness of both types of stars, they accurately determined the true brightness of the Type Ia supernovae. They then used this calibration to calculate distances to roughly 300 Type Ia supernovae in far-flung galaxies.

    “We needed both the nearby Cepheid distances for galaxies hosting Type Ia supernovae and the distances to the 300 more-distant Type Ia supernovae to determine the Hubble constant,” Filippenko said. “The paper focuses on the 19 galaxies and getting their distances really, really well, with small uncertainties, and thoroughly understanding those uncertainties.”

    Calibrating Cepheid Variable Stars

    “If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the Big Bang and use that understanding to predict how fast the universe should be expanding today,” said Riess. “However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today.”

    Aside from an increase in the strength with which dark energy is pushing the universe apart, and the existence of a new fundamental subatomic particle – a nearly speed-of-light particle called “dark radiation” – another possible explanation is that dark matter possesses some weird, unexpected characteristics. Dark matter is the backbone of the universe upon which galaxies built themselves into the large-scale structures seen today.

    *Science paper:
    A 2.4% Determination of the Local Value of the Hubble Constant

    See the full article here .
    See the NASA Hubble article here.
    See the ESA Hubble 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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 7:19 am on May 19, 2016 Permalink | Reply
    Tags: , , , Keck DEIMOS, Keck Observatory   

    From Keck: “Faintest Early-Universe Galaxy Ever, Detected and Confirmed” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    May 18, 2016
    Steve Jefferson

    2

    Color image of the cluster taken with Hubble Space Telescope (images in three different filters were combined to make an RGB image). In the inset we show three spectra of the multiply imaged systems. They have peaks at the same wavelength, hence showing that they belong to the same source.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    An international team of scientists has detected and confirmed the faintest early-Universe galaxy ever using the W. M. Keck Observatory on the summit on Maunakea, Hawaii. In addition to using the world’s most powerful telescope, the team relied on gravitational lensing to see the incredibly faint object born just after the Big Bang. The results are being published* in The Astrophysical Journal Letters today.

    The team detected the galaxy as it was 13 billion years ago, or when the Universe was a toddler on a cosmic time scale.

    The detection was made using the DEIMOS instrument fitted on the ten-meter Keck II telescope, and was made possible through a phenomenon predicted by Einstein in which an object is magnified by the gravity of another object that is between it and the viewer [gravitational lensing]. In this case, the detected galaxy was behind the galaxy cluster MACS2129.4-0741, which is massive enough to create three different images of the object.

    Keck/DEIMOS
    Keck/DEIMOS

    radio galaxies gravitationally lensed by a very large foreground galaxy cluster Hubble
    Radio galaxies gravitationally lensed by a very large foreground galaxy cluster Hubble

    “Keck Observatory’s telescopes are simply the best in the world for this work,” said Bradac. “Their power, paired with the gravitational force of a massive cluster of galaxies, allows us to truly see where no human has seen before.”

    “Because you see three of them and the characteristics are exactly the same, that means it was lensed,” said Marc Kassis, staff astronomer at Keck Observatory who assists the discovery team at night. “The other thing that is particularly interesting is that it is small. The only way they would have seen it is through lensing. This allowed them to identify it as an ordinary galaxy near the edge of the visible Universe.”

    “If the light from this galaxy was not magnified by factors of 11, five and two, we would not have been able to see it,” said Kuang-Han Huang, a team member from UC Davis and the lead author of the paper. “It lies near the end of the reionization epoch, during which most of the hydrogen gas between galaxies transitioned from being mostly neutral to being mostly ionized (and lit up the stars for the first time).

    Reionization era and first stars, Caltech
    Reionization era and first stars, Caltech

    That shows how gravitational lensing is important for understanding the faint galaxy population that dominates the reionization photon production.”

    The galaxy’s magnified images were originally seen separately in both Keck Observatory and Hubble Space Telescope data. The team collected and combined all the Keck Observatory/DEIMOS spectra from all three images, confirming they were the same and that this is a triply-lensed system.

    “We now have good constraints on when the reionization process ends – at redshift around 6 or 12.5 billion years ago – but we don’t yet know a lot of details about how it happened,” Huang said. “The galaxy detected in our work is likely a member of the faint galaxy population that drives the reionization process.”

    “This galaxy is exciting because the team infers a very low stellar mass, or only one percent of one percent of the Milky Way galaxy,” Kassis said. “It’s a very, very small galaxy and at such a great distance, it’s a clue in answering one of the fundamental questions astronomy is trying to understand: What is causing the hydrogen gas at the very beginning of the Universe to go from neutral to ionized about 13 billion years ago. That’s when stars turned on and matter became more complex.”

    The core of the team consisted of Bradac, Huang, Brian Lemaux, and Austin Hoag of UC Davis who are most directly involved with spectroscopic observation and data reduction of galaxies at redshift above seven. Keck Observatory astronomers Luca Rizzi and Carlos Alvarez were instrumental in helping the team collect the DEIMOS data. Tommaso Treu from University of California, Los Angeles and Kasper Schmidt of Leibniz Institute for Astrophysics Potsdam were also part of the team. They lead the effort that obtains and analyzes spectroscopic data from the WFC3/IR grism on Hubble.

    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 Maunakea 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 distant galaxies with DEIMOS, efficiently probing the most distant corners of the universe with high sensitivity.

    *Science paper:
    DETECTION OF LYMAN-ALPHA EMISSION FROM A TRIPLY IMAGED z = 6.85 GALAXY BEHIND MACS J2129.4−0741

    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 1:17 pm on May 11, 2016 Permalink | Reply
    Tags: , , Keck Observatory, Metal Content in Early Galaxies Challenges Star Forming Theory   

    From Keck: “Metal Content in Early Galaxies Challenges Star Forming Theory” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    May 10, 2016

    1
    A galaxy observed in this study (surrounded by a blue rectangle). The light we received from the galaxy in the distant Universe tells us – from hydrogen, oxygen, and neon emission lines – that they followed a different rule to produce the heavy elements. Credit: 3D-HST / NASA / ESA / STScI

    An International team led by scientists at ETH Zurich in Switzerland used the W. M. Keck Observatory to study the role of star formation rates in metal contents of distant galaxies.

    ETH Zurich bloc

    What they discovered is the amount of metals are very similar, irrespective of galaxies’ star formation activity, raising new questions about star-forming theory. Their findings were recently published* in the Astrophysical Journal.

    Using the MOSFIRE instrument installed on the Keck I telescope – one of the two world’s largest optical telescopes at Keck Observatory – the scientists gathered data on 41 normal, star-forming galaxies that were 11 billion light years away.

    Keck/MOSFIRE on Keck 1, muna Kea, Hawaii, USA
    Keck/MOSFIRE on Keck 1, muna Kea, Hawaii, USA

    The team found typical galaxies forming stars in the Universe two billion years after the Big Bang have only twenty percent of metals (elements heavier than Helium) compared with those in the present day Universe. They also discovered the metal content is independent of the strength of the star-formation activity – in stark contrast with what is known for recently formed, or nearby galaxies.

    “The galaxies we studied are very faint because they are so far away that light needs more than 11 billion years to reach us,” said Masato Onodera, the lead author of the paper. “Therefore, the superb light-gathering ability of the 10 meter Keck Observatory telescope was crucial to accomplish this study.”

    Gathering the photons is only part of the job, breaking it down into data that could be analyzed by the team was the job of Keck Observatory’s latest instrument, MOSFIRE.

    “MOSFIRE allowed us to observe multiple objects simultaneously with an exquisite sensitivity, enabling us to collect spectra of many galaxies very efficiently,” he said. “We saw number of spectral features emitted by ionized atoms in the galaxies such as hydrogen, oxygen, and neon, which allowed us to determine the metal content of the galaxies.”

    In addition to the telescope time awarded to them through the California Institute of Technology, the team exchanged valuable time on the 8-meter Subaru Telescope, also on Maunakea, for enough time on Keck Observatory to complete the research.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ Subaru Telescope interior
    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    Metal content in star-forming galaxies is the result of a complex interplay between gas coming into the galaxy, star formation in the galaxy, and gas outflowing from the galaxy in the cosmological context. How much metal is in the system and whether the correlation between the metal content and star formation activity exists provide important clues how galaxy evolve in a distant Universe.

    “If you extrapolate what is known in the local Universe, you would have expected a higher metallicity in less active star-forming galaxies than they found,” said Hien Tran, staff astronomer at Keck Observatory who was not part of the finding. “It’s part of the normal stellar and galaxy evolution. Onodera’s team realized the role of star formation is not as strong at great distances as it is at zero. Understanding the interplay between metallicity, star formation rates and the mass of star forming galaxies will help us better understand galaxy evolution.”

    Because the team did not see any influence of the strength of star formation in the metal enrichment in distant galaxies, it is telling that the physical condition regulating star formation in galaxies in the early Universe is possibly different from that seen in the present-day Universe. This could be related to the fact that star formation rate cannot keep up with the gas accretion rate from the cosmic web.

    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.

    *Science paper:
    A link will be added as soon as it is provided.

    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 7:31 pm on April 12, 2016 Permalink | Reply
    Tags: , , Keck Observatory, New Hypervelocity Binary Star Challenges Dark Matter and Stellar Acceleration Models   

    From Keck: “New Hypervelocity Binary Star Challenges Dark Matter, Stellar Acceleration Models” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    April 11, 2016
    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu

    SCIENCE CONTACTS
    Péter Németh
    Friedrich Alexander University (FAU), Erlangen-Nürnberg, Germany
    pnemeth1981@gmail.com
    +49 951 952 22 19

    Eva Ziegerer
    Friedrich Alexander University (FAU), Erlangen-Nürnberg, Germany
    Eva.Ziegerer@sternwarte.uni-erlangen.de
    +49 951 952 22 20

    Prof. Ulrich Heber
    Friedrich Alexander University (FAU), Erlangen-Nürnberg, Germany
    heber@sternwarte.uni-erlangen.de
    +49 951 952 22 14

    1
    PB3877 is a hyper-velocity wide binary star zooming through the outskirts of the Milky Way galaxy. This image shows its current location as well as our Sun. Credit: Thorsten Brand

    A team of astronomers at the Friedrich Alexander University led by Péter Németh has discovered a binary star moving nearly at the escape velocity of our galaxy. There are about two dozen so-called hypervelocity stars known to be escaping the galaxy. While all of them are single stars, PB3877 is the first wide binary star found to travel at such a high speed. Additionally, the results of the new study challenge the commonly accepted scenario that hypervelocity stars are accelerated by the supermassive black hole at the galactic center. The findings are being published* in the Astrophysical Journal Letters today.

    The team, in collaboration with researchers from the California Institute of Technology, showed the binary cannot originate from the Galactic Center, and no other mechanism is known that is able to accelerate a wide binary to such a high velocity without disrupting it. They therefore hypothesized there must be a lot of dark matter to keep the star bound to the Milky Way galaxy; or the binary star, PB3877, could be an intruder that has been born in another galaxy and may or may not leave the Milky Way again.

    PB3877 was first reported to be a hyper-velocity, hot compact star, when it was discovered form the Sloan Digital Sky-Survey (SDSS) data in 2011.

    SDSS Telescope at Apache Point, NM, USA
    SDSS Telescope at Apache Point, NM, USA

    New spectroscopic observations were done with the 10 meter Keck II telescope at W. M. Keck Observatory on Maunakea, Hawaii and with the 8.2 meter Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile.

    ESO/VLT
    ESO/VLT

    Caltech astronomers Thomas Kupfer and Felix Fürst observed PB3877 with the ESI Instrument fitted on the Keck II telescope.

    LBL/DESI spectroscopic instrument
    LBL/DESI spectroscopic instrument on Keck II

    “When we looked at the new data, much to our surprise, we found weak absorption lines that could not come from the hot star,” Kupfer said. “The cool companion, just like the hot primary, shows a high radial velocity. Hence, the two stars form a binary system, which is the first hyper-velocity wide binary candidate.”

    The surface of the hot compact star is more than five times hotter than the Sun, while the companion is a thousand degrees cooler than our Sun. The system was determined to be 18,000 light years away. The mass of the hot compact star is only half of the mass of our Sun, and the companion is .7 times the mass of the Sun.

    “We studied hyper-velocity stars since 2005, the year of discovery of the first three,” said team-member Ulrich Heber. “In the meantime about two dozen have been found, but all are single, none has a companion directly visible in its spectrum.”

    The center of our galaxy hosts a supermassive black hole that can accelerate and eject stars from the galaxy by disrupting an original binary star. Hence, most hyper-velocity stars are believed to originate from the galactic center.

    “From our calculations we can exclude the Galactic Center as the place of origin, because its trajectory never came close to it,” said team member Eva Ziegerer, specialist in stellar kinematics who collected the astrometry data and reconstructed the orbit of the binary. “Other ejection mechanisms, such as stellar collisions and a supernova explosion have been proposed, but all of them would lead to the disruption of a wide binary.”

    “PB3877 may be an intruder from another galaxy,” Németh said. “In that case its prolonged gradual acceleration would not harm its integrity. The outskirts of our Galaxy contain various stellar streams that are believed to be the remnants of dwarf galaxies that were torn to shreds by the strong tidal force of the Milky Way.”

    Unfortunately, the available data do not allow to make a connection to any of the known streams. Therefore, the origin of the binary remains unclear and so is its future. Whether or not the system remains bound to the Galaxy depends on the amount of dark matter in the Galaxy. Therefore, the mere existence of this binary puts pressure on our models and on our current understanding of dark matter in the Milky Way.

    “We used different mass models to calculate the probability that the star will actually remain bound to the Galaxy. Only for the most massive Galaxy model this is the case. This makes PB3877 an excellent target to probe dark matter halo models,” said Andreas Irrgang, research associate at the Dr. Karl Remeis-Observatory.


    The research continues with high-resolution spectroscopy to confirm the orbital properties of PB3877 and with a photometric follow-up to search for variability. “By finding further stars or binaries on similar orbits would indicate an external origin. Therefore, our quest for similar strangers will continue,” Németh said.

    *Science paper:
    AN EXTREMELY FAST HALO HOT SUBDWARF STAR IN A WIDE BINARY SYSTEM

    Science team:
    Péter Németh, 1; Eva Ziegerer, 1; Andreas Irrgang, 1; Stephan Geier, 1,2; Felix Fürst, 3; Thomas Kupfer, 3,4; and Ulrich Heber, 1

    Author affiliations

    1 Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg, Germany

    2 Department of Physics, University of Warwick, Coventry, CV4 7AL, UK

    3 Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA

    4 Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands

    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 5:35 pm on January 27, 2016 Permalink | Reply
    Tags: , , Keck Observatory, Laser frequency combs   

    From Keck: “New Calibration Tool Will Help Astronomers Look for Habitable Exoplanets” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    January 27, 2016
    Adam Hadhazy

    Promising new calibration tools, called laser frequency combs, could allow astronomers to take a major step in discovering and characterizing earthlike planets around other stars. These devices generate evenly spaced lines of light, much like the teeth on a comb for styling hair or the tick marks on a ruler — hence their nickname of “optical rulers.” The tick marks serve as stable reference points when making precision measurements such as those of the small shifts in starlight caused by planets pulling gravitationally on their parent stars.

    Yet today’s commercially available combs have a significant drawback. Because their tick marks are so finely spaced, the light output of these combs must be filtered to produce useful reference lines. This extra step adds complexity to the system and requires costly additional equipment.

    To resolve these kinds of issues, Caltech researchers looked to a kind of comb not previously deployed for astronomy. The novel comb produces easily resolvable lines, without any need for filtering. Furthermore, the Caltech comb is built from off-the-shelf components developed by the telecommunications industry.

    “We have demonstrated an alternative approach that is simple, reliable, and relatively inexpensive,” says paper coauthor Kerry Vahala, the Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics as well as the executive officer for Applied Physics and Materials Science in Caltech’s Division of Engineering and Applied Science. The kind of frequency comb used by the researchers previously has been studied in the Vahala group in a different application, the generation of high-stability microwaves.

    “We believe members of the astronomical community could greatly benefit in their exoplanet hunting and characterization studies with this new laser frequency comb instrument,” says Xu Yi, a graduate student in Vahala’s lab and the lead author of a paper describing the work published in the January 27, 2016, issue of the journal Nature Communications.

    Scientists first began widely using laser frequency combs as precision rulers in the late 1990s in fields like metrology and spectroscopy; for their work, the technology’s developers (John L. Hall of JILA and the National Institute of Standards and Technology (NIST) and Theodor Hänsch of the Max Planck Institute of Quantum Optics and Ludwig Maximilians University Munich) were awarded half of the Nobel Prize in Physics in 2005. In astronomy, the combs are starting to be utilized in the radial velocity, or “wobble” method, the earliest and among the most successful methods for identifying exoplanets.

    The “wobble” refers to the periodic changes in a star’s motion, accompanied by starlight shifts owing to the Doppler effect, that are induced by the gravitational pull of an exoplanet orbiting around the star. The magnitude of the shift in the starlight’s wavelength — on the order of quadrillionths of a meter — together with the period of the wobble can be used to determine an exoplanet’s mass and orbital distance from its star. These details are critical for assessing habitability parameters such as surface temperature and the eccentricity of the exoplanet’s orbit. With exoplanets that pass directly in front of (or “transit”) their host star, allowing their radius to be determined directly, it is even possible to determine the bulk composition — for example, if the planet is built up primarily of gas, ice, or rock.

    In recent years, so-called mode-locked laser combs have proven useful in this task. These lasers generate a periodic stream of ultrashort light pulses to create the comb. With such combs, however, approximately 49 out of every 50 tick marks must be blocked out. This requires temperature- and vibration-insensitive filtering equipment.

    The new electro-optical comb that the Caltech team studied relies on microwave modulation of a continuous laser source, rather than a pulsed laser. It produces comb lines spaced by tens of gigahertz. These lines have from 10 to 100 times wider spacing than the tick marks of pulsed laser combs.

    To see how well a prototype would work in the field, the researchers took their comb to Mauna Kea in Hawaii. In September 2014, the instrument was tested at the NASA Infrared Telescope Facility (IRTF);

    NASA Infrared Telescope facility
    IRTF

    in March 2015, it was tested with the Near Infrared Spectrometer on the W. M. Keck Observatory’s Keck II telescope with the assistance of UCLA astronomer Mike Fitzgerald (BS ’00) and UCLA graduate student Emily Martin, coauthors on the paper.

    The researchers found that their simplified comb (the entire electro-optical comb apparatus requires only half of the space available on a standard 19-inch instrumentation rack) provided steady calibration at room temperature for more than five days at IRTF. The comb also operated flawlessly during the second test—despite having been disassembled, stored for six months, and reassembled.

    “From a technological maturity point of view, the frequency comb we have developed is already basically ready to go and could be installed at many telescopes,” says paper coauthor Scott Diddams of NIST.

    The Caltech comb produces spectral lines in the infrared, making it ideal for studying red dwarf stars, the most common stars in the Milky Way. Red dwarf stars are brightest in infrared wavelengths. Because red dwarfs are small, cool, and dim, planets orbiting these types of stars are easier to detect and analyze than those orbiting hotter sun-like stars. NASA’s Kepler space observatory has shown that almost all red dwarf stars host planets in the range of one to four times the size of Earth, with up to 25 percent of these planets located in the temperate, or “habitable,” zone around their host stars.

    NASA Kepler Telescope
    NASA/Kepler

    Thus, many astronomers predict that red dwarfs provide the best chance for the first discovery of a world capable of supporting life.

    “Our goal is to make these laser frequency combs simple and sturdy enough that you can slap them onto every telescope, and you don’t have to think about them anymore,” says paper coauthor Charles Beichman, senior faculty associate in astronomy and the executive director of the NASA ExoPlanet Science Institute at Caltech. “Having these combs routinely available as a modest add-on to current and future instrumentation really will expand our ability to find potentially habitable planets, particularly around very cool red dwarf stars,” he says.

    The research team is planning to double the frequency of the prototype comb’s light output — now centered around 1,550 nanometers, in the infrared—to reach into the visible light range. Doing so would allow the comb also to calibrate spectra from sun-like stars, whose light output is at shorter, visible wavelengths, and thus seek out planets that are Earth’s “twins.”

    Other authors of the paper are Jiang Li, a visitor in applied physics and materials science, graduate students Peter Gao and Michael Bottom, and scientific research assistant Elise Furlan, all from Caltech; Stephanie Leifer, Jagmit Sandhu, Gautam Vasisht, and Pin Chen of JPL; Peter Plavchan (BS ’01), formerly at Caltech and now a professor at Missouri State University; G. Ycas of NIST; Jonathan Gagne of the University of Montréal; and Greg Doppmann of the Keck Observatory.

    The paper is titled Demonstration of a near-IR line-referenced electro-optical laser frequency comb for precision radial velocity measurements in astronomy. The research performed at Caltech and JPL was funded through the President’s and Director’s Fund Program, and the work at NIST was funded by the National Science Foundation.

    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 10:02 pm on January 11, 2016 Permalink | Reply
    Tags: , , Damped Lyman-alpha systems, Keck Observatory   

    From Keck: “Solved! 40 Year-old Mystery on the Size of Shadowy Galaxies” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    January 5, 2016
    Steve Jefferson
    Communication Officer
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu

    SCIENCE
    Jeff Cooke
    Swinburne University
    jcooke@astro.swin.edu.au

    John O’Meara
    St. Michael’s College
    jomeara@smcvt.edu

    Temp 1
    Artists impression of the power of background galaxies to measure the size of gas clouds as compared to the conventional method of using quasars. The plane to the far right shows the background galaxy and overlaid in the center of the galaxy is a bright white light representing a quasar. The DLA gas cloud is shown at the center of the plane in between the galaxy and Earth. The blue/white narrow beam indicates the small area of the DLA gas cloud probed by quasars, the wider red cone of light indicates the large area of the DLA probed by galaxies, which is a 100 million-fold increase in area. Credit: Adrian Malec (Swinburne University) and Marie Martig (Max Planck Institute for Astronomy, Heidelberg)

    Using the world’s largest telescopes, researchers discovered ancient cold gas clouds larger than galaxies in the early Universe. The discovery was announced today at a press conference at the 227th meeting of the American Astronomical Society in Orlando, Florida.

    The discovery, led by Associate Professor Jeff Cooke, Swinburne University of Technology, and Associate Professor John O’Meara, St. Michael’s College, has helped solve a decades-old puzzle on the nature of gas clouds, known as Damped Lyman-alpha systems, or DLAs.

    Cooke and O’Meara realized that finding DLA gas clouds in the line of sight to background galaxies would enable measurements of their size by determining how much of the galaxy they cover.

    “Our new method first identifies galaxies that are more likely to have intervening DLA gas clouds and then searches for them using long, deep exposures on the powerful Keck Observatory 10m telescopes on Maunakea and deep data from the VLT 8m telescopes in Chile,” Cooke said.

    ESO VLT Interferometer
    ESO/VLT

    “The technique is timely as the next generation of giant 30m telescopes will be online in several years and are ideal to take advantage of this method to routinely gather large numbers of DLAs for study.”

    DLA clouds contain most of the cool gas in the Universe and are predicted to contain enough gas to form most of the stars we see in galaxies around us today, like the Milky Way. However, this prediction has yet to be confirmed.

    DLAs currently have little ongoing star formation, making them too dim to observe directly from their emitted light alone. Instead, they are detected when they happen to fall in the line of sight to a more distant bright object and leave an unmistakeable absorption signature in the background object’s light.

    Previously, researchers used quasars as the background objects to search for DLAs. Although quasars can be very bright, they are rare and are comparatively small, only a fraction of a light year across, whereas galaxies are quite common and provide a 100 million-fold increase in area to probe DLAs.

    “Using the galaxy technique, DLAs can be studied in large numbers to provide a 3-D tomographic picture of distribution of gas clouds in the early Universe and help complete our understanding of how galaxies formed and evolved over cosmic time,” O’Meara said.

    See the full article here .

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