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  • richardmitnick 10:59 am on October 22, 2016 Permalink | Reply
    Tags: , , Io's volcanism, Keck Observatory   

    From Keck: “Long-Term, Hi-Res Tracking of Eruptions on Jupiter’s Moon Io” 

    Keck Observatory

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

    Keck Observatory

    October 20, 2016
    SCIENCE CONTACT
    Katherine de Kleer
    kdekleer@berkeley.edu

    Imke de Pater
    imke@berkeley.edu

    MEDIA CONTACT
    Bill Brown
    W. M. Keck Observatory
    (808) 881-3514

    1
    All hot spot detections from August 2013 through December 2015 shown on a full map of Io. Each circle represents a new detection; the size of the circle corresponds logarithmically to the intensity, and more opaque regions are where a hot spot was detected multiple times. The color and symbol indicate the type of eruption, following the legend. Loki Patera is at 310 West, 10 North and KurdalagonPatera is at 220 West, 50 South. Credit: Katherine de Kleer and Imke de Pater, UC Berkeley.

    Jupiter’s moon Io continues to be the most volcanically active body in the solar system, as documented by the longest series of frequent, high-resolution observations of the moon’s thermal emission ever obtained.

    Using near-infrared adaptive optics on two of the world’s largest telescopes– the 10-meter Keck II and the 8-meter Gemini North, both located near the summit of the dormant volcano Maunakea in Hawaii – University of California, Berkeley astronomers tracked 48 volcanic hotspots on the surface over a period of 29 months from August 2013 through the end of 2015.

    Gemini/North telescope at Mauna Kea, Hawaii, USA
    Gemini/North telescope at Mauna Kea, Hawaii, USA

    2
    Images of Io at different near-infrared wavelengths; the name of the filter is indicated in the black box at the start of each section. The bright spots are thermal emissions from Io’s myriad volcanoes. Note the increasing number of hot spots detected at longer wavelengths, i.e. towards the bottom of the figure. Credit: Katherine de Kleer and Imke de Pater, UC Berkeley

    Without adaptive optics – a technique that removes the atmospheric blur to sharpen the image – Io is merely a fuzzy ball. Adaptive optics can separate features just a few hundred kilometers apart on Io’s 3,600-kilometer-diameter surface.

    “On a given night, we may see half a dozen or more different hot spots,” said Katherine de Kleer, a UC Berkeley graduate student who led the observations. “Of Io’s hundreds of active volcanoes, we have been able to track the 50 that were the most powerful over the past few years.”

    She and Imke de Pater, a UC Berkeley professor of astronomy and of earth and planetary science, observed the heat coming off of active eruptions as well as cooling lava flows and were able to determine the temperature and total power output of individual volcanic eruptions.They tracked their evolution over days, weeks and sometimes even years.

    Interestingly, some of the eruptions appeared to progress across the surface over time, as if one triggered another 500 kilometers away.

    “While it stretches the imagination to devise a mechanism that could operate over distances of 500 kilometers, Io’s volcanism is far more extreme than anything we have on Earth and continues to amaze and baffle us,” de Kleer said.

    De Kleer and de Pater will discuss their observations at a media briefing on Oct. 20 during a joint meeting of the American Astronomical Society’s Division for Planetary Sciences and the European Planetary Science Congress in Pasadena, California. Papers describing the observations have been accepted for future publication by the journal Icarus.

    Tidal heating

    Io’s intense volcanic activity is powered by tidal heating — heating from friction generated in Io’s interior as Jupiter’s intense gravitational pull changes by small amounts alongIo’s orbit. Models for how this heating occurs predict that most of Io’s total volcanic power should be emitted either near the poles or near the equator, depending on the model, and that the pattern should be symmetric between the forward- and backward-facing hemispheres in Io’s orbit (that is, at longitudes 0-180 degrees versus 180-360 degrees).

    That’s not what they saw. Over the observational period, August 2013 through December 2015, the team obtained images of Io on 100 nights. Though they saw a surprising number of short-lived but intense eruptions that appeared suddenly and subsided in a matter of days, every single one took place on the trailing face of Io (180-360 degrees longitude) rather than the leading face, and at higher latitudes than more typical eruptions.

    “The distribution of the eruptions is a poor match to the model predictions,” de Kleer said, “but future observations will tell us whether this is just because the sample size is too small, or because the models are too simplified. Or perhaps we’ll learn that local geological factors play a much greater role in determining where and when the volcanoes erupt than the physics of tidal heating do.”

    One key target of interest was Io’s most powerful persistent volcano, Loki Patera, which brightens by more than a factor of 10 every 1-2 years. A patera is an irregular crater, usually volcanic.

    Many scientists believe that Loki Patera is a massive lava lake, and that these bright episodes represent its overturning crust, like that seen in lava lakes on Earth. In fact, the heat emissions from Loki Patera appear to travel around the lake during each event, as if from a wave moving around a lake triggering the destabilization and sinking of portions of crust. Prior to 2002, this front seemed to travel around the cool island in the center of the lake in a counter-clockwise direction.

    After an apparent cessation of brightening events after 2002, de Pater observed renewed activity in 2009.

    “With the renewed activity, the waves traveled clockwise around the lava lake,” she noted.

    Another volcano, Kurdalagon Patera, produced unusually hot eruptions twice in the spring of 2015, coinciding with the brightening ofan extended cloud of neutral material that orbits Jupiter.This provides circumstantial evidence that eruptions on the surface are the source of variability in this neutral cloud, though it’s unclear why other eruptions were not also associated with brightening, de Kleer said.

    De Kleer noted that the Keck and Gemini telescopes, both atop the dormant volcano Maunakea, complement one another. Gemini North’s queue scheduling allowed more frequent observations – often several a week – while Keck’s instruments are sensitive also to longer wavelengths (5 microns), showing cooler features such as older lava flows that are invisible in the Gemini observations.

    The astronomers are continuing their frequent observations of Io, providing a long-term database of high spatial resolution images that not even Galileo, which orbited Jupiter for eight years, was able to achieve.

    The work is supported by a grant from the National Science Foundation (AST-1313485)and de Kleer’s NSF Graduate Research Fellowship(DGE-1106400).

    Link to science paper.
    Link to science paper.

    See the full article here .

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    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 1:10 pm on September 13, 2016 Permalink | Reply
    Tags: , , Explaining Why the Universe Can Be Transparent, Keck Observatory,   

    From UC Riverside: “Explaining Why the Universe Can Be Transparent” 

    UC Riverside bloc

    UC Riverside

    September 12, 2016
    Sean Nealon

    1
    Reionization as illustrated by data from the Hubble and Chandra space telescopes. Credit: NASA/CXC/M.Weiss.

    Two papers published by an assistant professor at the University of California, Riverside and several collaborators explain why the universe has enough energy to become transparent.

    The study led by Naveen Reddy, an assistant professor in the Department of Physics and Astronomy at UC Riverside, marks the first quantitative study of how the gas content within galaxies scales with the amount of interstellar dust.

    This analysis shows that the gas in galaxies is like a “picket fence,” where some parts of the galaxy have little gas and are directly visible, whereas other parts have lots of gas and are effectively opaque to ionizing radiation. The findings were just published in The Astrophysical Journal.

    The ionization of hydrogen is important because of its effects on how galaxies grow and evolve. A particular area of interest is assessing the contribution of different astrophysical sources, such as stars or black holes, to the budget of ionizing radiation.

    Most studies suggest that faint galaxies are responsible for providing enough radiation to ionize the gas in the early history of the universe. Moreover, there is anecdotal evidence that the amount of ionizing radiation that is able to escape from galaxies depends on the amount of hydrogen within the galaxies themselves.

    The research team led by Reddy developed a model that can be used to predict the amount of escaping ionizing radiation from galaxies based on straightforward measurements on how “red,” or dusty, their spectra appear to be.

    Alternatively, with direct measurements of the ionizing escape fraction, their model may be used to constrain the intrinsic production rate of ionizing photons at around two billion years after the Big Bang.

    These practical applications of the model will be central to the interpretation of escaping radiation during the cosmic “dark ages,” a topic that is bound to flourish with the coming of 30-meter telescopes, which will allow for research unfeasible today, and the James Webb Space Telescope, NASA’s next orbiting observatory and the successor to the Hubble Space Telescope.

    The research ties back to some 400,000 years after the Big Bang, when the universe entered the cosmic “dark ages,” where galaxies and stars had yet to form amongst the dark matter, hydrogen and helium.

    A few hundred million years later, the universe entered the “Epoch of Reionization,” where the gravitational effects of dark matter helped hydrogen and helium coalesce into stars and galaxies. A great amount of ultraviolet radiation (photons) was released, stripping electrons from surrounding neutral environments, a process known as “cosmic reionization.”

    Reionization, which marks the point at which the hydrogen in the Universe became ionized, has become a major area of current research in astrophysics. Ionization made the Universe transparent to these photons, allowing the release of light from sources to travel mostly freely through the cosmos.

    The data for this research was acquired through the low resolution imaging spectrograph on the W.M. Keck Observatory.

    Keck Observatory, Mauna Kea, Hawaii, USA
    Keck Observatory Interior
    Keck Observatory, Mauna Kea, Hawaii, USA

    The collaborators of this research are Charles Steidel (Caltech), Max Pettini (University of Cambridge), Milan Bogosavljevic (Astronomical Observatory, Belgrade) and Alice Shapley (UCLA).

    The papers are Spectroscopic Measurements of the Far-Ultraviolet Dust Attenuation Curve at z~3 and The Connection Between Reddening, Gas Covering Fraction, and the Escape of Ionizing Radiation at High Redshift.

    See the full article here .

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    UC Riverside Campus

    The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

    Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

    We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

     
  • richardmitnick 9:19 am on September 7, 2016 Permalink | Reply
    Tags: Astronomers Discover Rare Fossil Relic of Early Milky Way, , , , Keck Observatory, , Terzan 5   

    From ESO and Hubble: “Astronomers Discover Rare Fossil Relic of Early Milky Way” 

    ESO 50 Large

    European Southern Observatory

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    7 September 2016
    Francesco Ferraro
    Università degli Studi di Bologna
    Bologna, Italy
    Tel: +39 051 20 9 5774
    Email: francesco.ferraro3@unibo.it

    Davide Massari
    INAF – Osservatorio Astronomico di Bologna
    Bologna, Italy
    Tel: +51 2095318
    Email: davide.massari@oabo.inaf.it

    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Tel: +49 176 62397500
    Email: mjaeger@partner.eso.org

    1

    Using ESO’s Very Large Telescope and other telescopes a fossilised remnant of the early Milky Way harbouring stars of hugely different ages has been revealed by an international team of astronomers. This stellar system resembles a globular cluster, but is like no other cluster known. It contains stars remarkably similar to the most ancient stars in the Milky Way and bridges the gap in understanding between our galaxy’s past and its present.

    Terzan 5, 19 000 light-years from Earth in the constellation of Sagittarius (the Archer) and in the direction of the galactic centre, has been classified as a globular cluster for the forty-odd years since its detection. Now, an Italian-led team of astronomers have discovered that Terzan 5 is like no other globular cluster known.

    The team scoured data from the Multi-conjugate Adaptive Optics Demonstrator [MAD] [1], installed at the Very Large Telescope, as well as from a suite of other ground-based and space telescopes [2]. They found compelling evidence that there are two distinct kinds of stars in Terzan 5 which not only differ in the elements they contain, but have an age-gap of roughly 7 billion years [3].

    ESO MAD bench
    ESO MAD

    The ages of the two populations indicate that the star formation process in Terzan 5 was not continuous, but was dominated by two distinct bursts of star formation. “This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive. At least 100 million times the mass of the Sun,” explains Davide Massari, co-author of the study, from INAF, Italy, and the University of Groningen, Netherlands.

    Its unusual properties make Terzan 5 the ideal candidate for a living fossil from the early days of the Milky Way. Current theories on galaxy formation assume that vast clumps of gas and stars interacted to form the primordial bulge of the Milky Way, merging and dissolving in the process.

    “We think that some remnants of these gaseous clumps could remain relatively undisrupted and keep existing embedded within the galaxy,” explains Francesco Ferraro from the University of Bologna, Italy, and lead author of the study. “Such galactic fossils allow astronomers to reconstruct an important piece of the history of our Milky Way.”

    While the properties of Terzan 5 are uncommon for a globular cluster, they are very similar to the stellar population which can be found in the galactic bulge, the tightly packed central region of the Milky Way. These similarities could make Terzan 5 a fossilised relic of galaxy formation, representing one of the earliest building blocks of the Milky Way.

    This assumption is strengthened by the original mass of Terzan 5 necessary to create two stellar populations: a mass similar to the huge clumps which are assumed to have formed the bulge during galaxy assembly around 12 billion years ago. Somehow Terzan 5 has managed to survive being disrupted for billions of years, and has been preserved as a remnant of the distant past of the Milky Way.

    “Some characteristics of Terzan 5 resemble those detected in the giant clumps we see in star-forming galaxies at high-redshift, suggesting that similar assembling processes occurred in the local and in the distant Universe at the epoch of galaxy formation,“ continues Ferraro.

    Hence, this discovery paves the way for a better and more complete understanding of galaxy assembly. “Terzan 5 could represent an intriguing link between the local and the distant Universe, a surviving witness of the Galactic bulge assembly process,” explains Ferraro while commenting on the importance of the discovery. The research presents a possible route for astronomers to unravel the mysteries of galaxy formation, and offers an unrivaled view into the complicated history of the Milky Way.
    Notes

    [1] The Multi-Conjugate Adaptive Optics Demonstrator (MAD) is a prototype multi-conjugate adaptive optics system which aims to demonstrate the feasibility of different MCAO reconstruction techniques in the framework of the E-ELT concept and the second generation VLT Instruments.

    [2] The researchers also used data from the Advanced Camera for Surveys [ACS]and the Wide Field Camera 3 [WFC3] on board the NASA/ESA Hubble Space Telescope and NIRC2 (the Near-Infrared Camera, second generation) at the W. M. Keck Observatory.

    NASA/ESA Hubble ACS
    “NASA/ESA Hubble ACS

    NASA Hubble WFC3
    NASA/ESA Hubble WFC3

    Keck Observatory, Mauna Kea, Hawaii, USA
    Keck Observatory, Mauna Kea, Hawaii, USA

    Keck NIRC2 Camera
    Keck NIRC2 Camera

    [3] The two detected stellar populations have ages of 12 billion years and 4.5 billion years respectively.

    More information

    Link to science paper.

    The team is composed of F. R. Ferraro (Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Italy) , D. Massari (INAF – Osservatorio Astronomico di Bologna, Italy & Kapteyn Astronomical Institute, University of Groningen, Netherlands), E. Dalessandro (Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Italy; INAF – Osservatorio Astronomico di Bologna, Italy) , B. Lanzoni (Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Italy), L. Origlia (INAF – Osservatorio Astronomico di Bologna, Italy), R. M. Rich (Department of Physics and Astronomy, University of California, Los Angeles, USA) and A. Mucciarelli (Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Italy).

    See the full ESO article here .

    See the full Hubble article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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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 .

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    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.
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  • 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.
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  • 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

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  • 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.
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  • 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.

    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.
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  • 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

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    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 .

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    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.
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