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  • richardmitnick 2:22 pm on January 17, 2017 Permalink | Reply
    Tags: Astronomy, , , Habitable zones, SF State,   

    From SF State: “SF State astronomer searches for signs of life on Wolf 1061 exoplanet” 

    SFSU bloc

    San Fransisco State University

    January 13, 2017
    Jamie Oppenheim

    1
    An artist’s rendering of an exoplanet is shown. An exoplanet is a planet that exists outside Earth’s solar system. Illustration credit: NASA/Ames/JPL-Caltech

    SF State astronomer Stephen Kane searches for signs of life in one of the extrasolar systems closest to Earth.

    Is there anybody out there? The question of whether Earthlings are alone in the universe has puzzled everyone from biologists and physicists to philosophers and filmmakers. It’s also the driving force behind San Francisco State University astronomer Stephen Kane’s research into exoplanets — planets that exist outside Earth’s solar system.

    As one of the world’s leading “planet hunters,” Kane focuses on finding “habitable zones,” areas where water could exist in a liquid state on a planet’s surface if there’s sufficient atmospheric pressure. Kane and his team, including former undergraduate student Miranda Waters, examined the habitable zone on a planetary system 14 light years away. Their findings will appear in the next issue of Astrophysical Journal in a paper titled Characterization of the Wolf 1061 Planetary System.

    “The Wolf 1061 system is important because it is so close and that gives other opportunities to do follow-up studies to see if it does indeed have life,” Kane said.

    But it’s not just Wolf 1061’s proximity to Earth that made it an attractive subject for Kane and his team. One of the three known planets in the system, a rocky planet called Wolf 1061c, is entirely within the habitable zone. With assistance from collaborators at Tennessee State University and in Geneva, Switzerland, they were able to measure the star around which the planet orbits to gain a clearer picture of whether life could exist there.

    When scientists search for planets that could sustain life, they are basically looking for a planet with nearly identical properties to Earth, Kane said. Like Earth, the planet would have to exist in a sweet spot often referred to as the “Goldilocks zone” where conditions are just right for life. Simply put, the planet can’t be too close or too far from its parent star. A planet that’s too close would be too hot. If it’s too far, it may be too cold and any water would freeze, which is what happens on Mars, Kane added.

    Conversely, when planets warm, a “runaway greenhouse effect” can occur where heat gets trapped in the atmosphere. Scientists believe this is what happened on Earth’s twin, Venus. Scientists believe Venus once had oceans, but because of its proximity to the sun the planet became so hot that all the water evaporated, according to NASA. Since water vapor is extremely effective in trapping in heat, it made the surface of the planet even hotter. The surface temperature on Venus now reaches a scalding 880 degrees Fahrenheit.

    Since Wolf 1061c is close to the inner edge of the habitable zone, meaning closer to the star, it could be that the planet has an atmosphere that’s more similar to Venus. “It’s close enough to the star where it’s looking suspiciously like a runaway greenhouse,” Kane said.

    Kane and his team also observed that unlike Earth, which experiences climatic changes such as an ice age because of slow variations in its orbit around the sun, Wolf 1061c’s orbit changes at a much faster rate, which could mean the climate there could be quite chaotic. “It could cause the frequency of the planet freezing over or heating up to be quite severe,” Kane said.

    These findings all beg the question: Is life possible on Wolf 1061c? One possibility is that the short time scales over which Wolf 1061c’s orbit changes could be enough that it could actually cool the planet off, Kane said. But fully understanding what’s happening on the planet’s surface will take more research.

    In the coming years, there will be a launch of new telescopes like the James Webb Space Telescope, the successor to the Hubble Space Telescope, Kane said, and it will be able to detect atmospheric components of the exoplanets and show what’s happening on the surface.

    See the full article here .

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    SFSU Campus

    San Francisco State University (commonly referred to as San Francisco State, SF State and SFSU) is a public comprehensive university located in San Francisco, California, United States. As part of the 23-campus California State University system, the university offers 118 different Bachelor’s degrees, 94 Master’s degrees, 5 Doctoral degrees including two Doctor of Education, a Doctor of Physical Therapy, a Ph.D in Education and Doctor of Physical Therapy Science, along with 26 teaching credentials among six academic colleges.

     
  • richardmitnick 1:41 pm on January 17, 2017 Permalink | Reply
    Tags: Astronomy, , , Gaia: The Stars in Motion   

    From astrobites: “Gaia: The Stars in Motion” 

    Astrobites bloc

    Astrobites

    Jan 17, 2017
    Philipp Plewa

    Title: First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion And Rotation
    Authors: R. P. van der Marel & J. Sahlmann
    First Author’s Institution: Space Telescope Science Institute
    1
    Status: Published in The Astrophysical Journal Letters, open access

    Although the night sky seems unchanging, it is in constant motion. Stars are not stationary objects but move through space, just like the Sun is moving along an orbit around the center of the Milky Way. A consequence is that all of today’s well-known constellations will eventually become unrecognizable (after a few hundred thousand years).

    2
    Figure 1 The proper motion of a star is its apparent (angular) motion on the sky, which reflects the transverse component of its true motion (Figure from the RAVE collaboration).

    The apparent motions of individual stars on the sky are called proper motions (Fig. 1) and the study of such motions is part of a field called astrometry. A revolutionary satellite dedicated to precision astrometry, Hipparcos, was launched in 1989 and provided a comprehensive catalog of the motions of stars in the backyard of the Solar System, which grew to include 2.5 million stars. Its modern successor, Gaia, was launched in 2013 and will reveal the motions of about a billion stars in total.

    ESA/GAIA satellite
    ESA/GAIA satellite

    The authors of today’s paper focus on using Gaia to study the Large Magellanic Cloud (LMC).

    Large Magellanic Cloud. Adrian Pingstone  December 2003
    Large Magellanic Cloud. Adrian Pingstone December 2003

    The LMC is the most massive satellite galaxy orbiting the Milky Way, and a prominent feature in the southern night sky. In the latest Tycho-Gaia catalog, there are 29 stars that have been identified as likely members of the LMC. The typical proper motion of these bright young stars is about 1.8 mas (or 2 millionths of a degree) per year, which corresponds to an actual velocity of around 430 kilometers per second at the distance of the LMC (approximately 50.1 kpc, or 6 times the distance to the Galactic Center). The measurement precision of 0.15 mas/yr is extraordinary, considering that 0.1 mas on the sky is roughly the apparent size of a frisbee on the Moon.

    3
    Figure 2 The observed velocity pattern of stars in the Large Magellanic Cloud (yellow arrows) reveals a rotating disk structure. The bottom left inset shows the average velocity that has been subtracted, while the bottom right inset shows the typical measurement uncertainty. (Figure 1 in the paper.)

    he observed velocity pattern of the stars can be separated into a linear average motion and a clockwise peculiar motion (Fig. 2), which is evidence for a rotating disk structure. This rather large proper motion of the LMC and its internal rotation have already been found by previous studies (e.g. van der Marel & Kallivayalil 2014). It is testing the reproducibility of these results that is the authors’ main goal, as well as exploring the capabilities of Gaia. The authors have also performed essentially the same analysis on a completely independent data set obtained with yet another satellite, the Hubble Space Telescope. It is reassuring that the results indeed turn out consistent, which means that the underlying approaches are sound and that there are no lingering systematic uncertainties.

    The rotation curve inferred from the proper motion data also matches the line-of-sight (“radial”) velocities of other stars in the LMC. Taken together, these data sets can be used to estimate the distance to the LMC, based purely on observations of the stellar dynamics. Photometric methods, based on measuring the luminosities of stars (e.g. Freedman et al. 2001), yield more precise estimates (at least for now), but again two independent approaches lead to the same consistent result.

    Astrometry and the study of stellar motions in the LMC, the Milky Way and other stellar systems is critical in understanding their structure and history (see Lucia’s post on “The Fate of the Milky Way”). After the initial data release of the Gaia mission, this paper was one of the first to be submitted. And even though this data set is still limited, it immediately led to some new and exciting insights. All things considered, the wealth of high-quality data yet to be released certainly has the potential to revolutionize this field once again, starting in (fingers crossed) late 2017. Feel free continue reading Ben’s post on Gaia’s potential for finding exoplanets.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 1:03 pm on January 17, 2017 Permalink | Reply
    Tags: , Astronomy, ,   

    From ALMA: “ALMA Starts Observing the Sun” This is a Blast 

    ALMA Array

    ALMA

    17 January 2017
    Nicolás Lira T.
    Press Coordinator
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 24 67 65 19
    Cell: +56 9 94 45 77 26
    Email: nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Masaaki Hiramatsu

    Education and Public Outreach Officer, NAOJ Chile
    Observatory
Tokyo, Japan

    Tel: +81 422 34 3630

    E-mail: hiramatsu.masaaki@nao.ac.jp

    1
    This image of the entire Sun was taken at a wavelength of 617.3 nm. Light at this wavelength originates from the visible solar surface, the photosphere. A cooler, darker sunspot is clearly visible in the disk, and — as a visual comparison — a depiction from ALMA at a wavelength of 1.25 millimeters is shown. Credit: ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF) | Full-disc solar image: Filtergram taken in Fe I 617.3 nm spectral line with the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). Credit: NASA

    NASA/SDO
    NASA/SDO

    New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot nearly twice as large as the diameter of the Earth. These images are part of the testing and verification campaign to make ALMA’s solar observing capabilities available to the international astronomical community.

    Though designed principally to observe remarkably faint objects throughout the Universe — such as distant galaxies and planet-forming disks around young stars – ALMA is also capable of studying objects in our own Solar System, including planets, comets, and now our own Sun.

    2
    This ALMA image of an enormous sunspot was taken on 18 December 2015 with the Band 6 receiver at a wavelength of 1.25 millimeters. Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than their surrounding regions, which is why they appear relatively dark in visible light. The ALMA image is essentially a map of temperature differences in a layer of the Sun’s atmosphere known as the chromosphere, which lies just above the visible surface of the Sun (the photosphere). The chromosphere is considerably hotter than the photosphere. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed by ALMA. Observations at shorter wavelengths probe deeper into the solar chromosphere than longer wavelengths. Hence, Band 6 observations map a layer of the chromosphere that is closer to the visible surface of the Sun than Band 3 observations. Credit: ALMA (ESO/NAOJ/NRAO)

    During a 30-month period beginning in 2014, an international team of astronomers harnessed ALMA’s single-antenna and array capabilities to detect and image the millimeter-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, the visible surface of the Sun.

    4
    ALMA image of an enormous sunspot taken on 18 December 2015 with the Band 3 receiver at a wavelength of 3 millimeters. Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than their surrounding regions, which is why they appear relatively dark in visible light. The ALMA images are essentially maps of temperature differences in a layer of the Sun’s atmosphere known as the chromosphere, which lies just above the visible surface of the Sun (the photosphere). The chromosphere is considerably hotter than the photosphere. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed by ALMA. Observations at shorter wavelengths probe deeper into the solar chromosphere than longer wavelengths. Hence, Band 6 observations map a layer of the chromosphere that is closer to the visible surface of the Sun than Band 3 observations. Credit: ALMA (ESO/NAOJ/NRAO)

    These new images demonstrate ALMA’s ability to study solar activity at longer wavelengths than observed with typical solar telescopes on Earth, and are an important expansion of the range of observations that can be used to probe the physics of our nearest star.

    5
    This full map of the Sun at a wavelength of 1.25 mm was taken with a single ALMA antenna using a so-called “fast-scanning” technique. The accuracy and speed of observing with a single ALMA antenna makes it possible to produce a low-resolution map of the entire solar disk in just a few minutes. Such images can be used in their own right for scientific purposes, showing the distribution of temperatures in the chromosphere, the region of the solar atmosphere that lies just above the visible surface of the Sun. Credit: ALMA (ESO/NAOJ/NRAO)

    “We’re accustomed to seeing how our Sun appears in visible light, but that can only tell us so much about the dynamic surface and energetic atmosphere of our nearest star,” said Tim Bastian, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Virginia in the USA. “To fully understand the Sun, we need to study it across the entire electromagnetic spectrum, including the millimeter and submillimeter portion that ALMA can observe.”

    Since our Sun is many billions of times brighter than the faint objects ALMA typically observes, the solar commissioning team had to developed special procedures to enable ALMA to safely image the Sun without damaging its sensitive electronics.

    The result of this work is a series of images that demonstrates ALMA’s unique vision and ability to study our Sun on multiple scales.

    The ALMA Solar Development Team includes Shin’ichiro Asayama, East Asia ALMA Support Center, Tokyo, Japan; Miroslav Barta, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Tim Bastian, National Radio Astronomy Observatory, USA; Roman Brajsa, Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia; Bin Chen, New Jersey Institute of Technology, USA; Bart De Pontieu, LMSAL, USA; Gregory Fleishman, New Jersey Institute of Technology, USA; Dale Gary, New Jersey Institute of Technology, USA; Antonio Hales, Joint ALMA Observatory, Chile; Akihiko Hirota, Joint ALMA Observatory, Chile; Hugh Hudson, School of Physics and Astronomy, University of Glasgow, UK; Richard Hills, Cavendish Laboratory, Cambridge, UK; Kazumasa Iwai, National Institute of Information and Communications Technology, Japan; Sujin Kim, Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea; Neil Philips, Joint ALMA Observatory, Chile; Tsuyoshi Sawada, Joint ALMA Observatory, Chile; Masumi Shimojo, NAOJ, Tokyo, Japan; Giorgio Siringo, Joint ALMA Observatory, Chile; Ivica Skokic, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Sven Wedemeyer, Institute of Theoretical Astrophysics, University of Oslo, Norway; Stephen White, AFRL, USA; Pavel Yagoubov, ESO, Garching, Germany; and Yihua Yan, NAO, Chinese Academy of Sciences, Beijing, China.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

    NRAO Small

    ESO 50

    NAOJ

     
  • richardmitnick 12:25 pm on January 17, 2017 Permalink | Reply
    Tags: , Astronomy, , , , Orion Nebula Hubble and VLT, So what does a molecular cloud produce anyway?   

    From astrobites: “So what does a molecular cloud produce, anyway?” 

    Astrobites bloc

    Astrobites

    Title: The bimodal initial mass function in the Orion Nebula Cloud
    Authors: H. Drass, M. Haas, R. Chini, A. Bayo, M. Hackstein, V. Hoffmeister, N. Godoy, N. Vogt
    First Author’s Institutions: Ruhr-Universität Bochum & Pontifica Universidad Católica de Chile
    1
    2
    Status: Published in MNRAS [open access]

    Introduction

    Collapsing regions of molecular clouds produce objects with a range of masses, from teeny planets to stars that are a hundred times the mass of the Sun. The ‘initial mass function’ plots the relative number of bodies as a function of mass. What does the initial mass function look like? And how much does it depend on the local environment? The distribution is determined by the poorly-constrained processes of star formation, which involve physics of the evolution of structure, chemistry, and star formation rates of galaxies, as well as the formation and evolution of stellar and exoplanetary systems. If we can determine the initial mass function exactly, we can help make some headway in these disparate fields.

    There are two alternative theories for how the initial mass function may be formed: the parent core masses in collapsing molecular clouds map directly to the initial mass function, or gravitational interactions affect accretion onto protostars and fling members out of multiple-object systems. It is difficult to tell which effect is most important because, well, it is difficult to measure the initial mass function precisely. Low-mass objects are very dim, and some fade away into complete invisibility as they cool. High-mass stars are easy to detect, but they burn faster and quickly blow away their atmospheres or explode as supernovae.

    The paper

    In this paper, Drass et al. strategically chose to survey the Orion Nebular Cloud (Fig. 1), which is only 1,350 light-years (414 parsecs) away and has produced stars that have not yet been churned around in the Milky Way like the siblings of our own Sun. It is very young, perhaps a couple million years old– so low-mass objects are still glowing with the heat of formation and the first generation of high-mass stars is still present.

    1
    Fig. 1: The Orion Nebula Cloud, with the footprints of different surveys. Drass et al.’s footprint is in black. The circled region is the nebula M43, which Drass et al. removed from their analysis because it may have an initial mass function distinct from the cloud as a whole. (Adapted from Drass et al., Fig. 1; HST images were taken with ACS B, V, H-alpha, I, and Z filters.)

    Orion Nebula M. Robberto NASA ESA Space Telescope Science Institute Hubble
    Orion Nebula M. Robberto NASA ESA Space Telescope Science Institute Hubble

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Orion Nebula VLT
    Orion Nebula VLT

    The authors used the Very Large Telescope in the Atacama Desert in Chile with 1.25, 1.65, and 2.15 micron filters, in which small-mass objects are relatively bright.
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    This filter combination also allows each star to be placed on a color-magnitude diagram, which, in combination with models, determines stellar masses or temperatures.

    Drass et al. removed contaminants and overlaid their color-magnitude diagrams with lines called ‘isochrones‘, which indicate model locations of stars of different masses. These were used to convert the colors of the detected stars to actual masses. Voilà– the end result is an initial mass function.

    Conclusion

    Surprisingly, the mass function corresponding to an age of 2-5 million years has two distinct peaks (Fig. 2)! If the Orion Nebula is indeed that old (some think it might actually be younger) and if the isochrones are accurate (isochrones are debatable at the lowest masses), then the Orion Nebular Cloud seems to be preferentially producing objects at around 0.25 and 0.025 solar masses. These correspond to low-mass stars and brown dwarfs. There are also, the authors note, some free-floating planets below the brown dwarf range.

    Drass et al. suggest that this mass function is evidence against a pure one-to-one mapping of the core mass and initial mass functions. Dynamical interactions may indeed have played a role by whipping low-mass objects out of interacting systems and littering the Orion Nebula with orphaned, low-mass objects. It is not possible to definitively prove this with current models, but the authors suggest the answer “has to be searched for along that direction.”

    2
    Fig. 2: Here is the final initial (eh? ) mass function of the Orion Nebula (black line). Different data points were generated using different filter combinations and give a sense of the uncertainty. Green corresponds to the mass function of another region in Orion with very high extinction, where background contaminants are masked by the intervening gas. Red shows the component of the green that is just due to brown dwarfs, and dashed lines show model initial mass functions from the literature. The similarity between the green and the black suggest that contaminants have been adequately accounted for, and that the bimodal nature of the initial mass function is real. (Drass et al., Fig. 12.)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 2:34 pm on January 16, 2017 Permalink | Reply
    Tags: Astronomy, , , brightest galaxies shine a ghostly green in surprising new find, , Earliest,   

    From Ethan Siegel: “Earliest, brightest galaxies shine a ghostly green in surprising new find” 

    From Ethan Siegel
    1.16.17

    Only a few galaxies exhibit this green glow in the nearby Universe. At early times, it’s practically all of the brightest ones.

    1
    Some rare galaxies exhibit a green glow thanks to the presence of doubly ionized oxygen. This requires UV light from stellar temperatures of 50,000 K and above. Image credit: NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa), of NGC 5972.

    “The discovery that young galaxies are so unexpectedly bright–if you look for this distinctive green light–will dramatically change and improve the way that we study Galaxy formation throughout the history of the Universe.”
    -Matthew Malkan

    Here in the nearby Universe, 13.8 billion years since the Big Bang, galaxies come in great varieties.

    2
    A great variety of galaxies in color, morphology, age and inherent stellar populations can be seen in this deep-field image. Image credit: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, and M. Rutkowski (Arizona State University, Tempe), R. O’Connell (University of Virginia), P. McCarthy (Carnegie Observatories), N. Hathi (University of California, Riverside), R. Ryan (University of California, Davis), H. Yan (Ohio State University), and A. Koekemoer (Space Telescope Science Institute).

    Spirals, ellipticals, rings and irregulars, they glow blue, white or red, depending on their stellar populations.

    3
    Galaxies undergoing massive bursts of star formation expel large quantities of matter at great speeds. They also glow red covering the whole galaxy, thanks to hydrogen emissions. Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA), of the Cigar Galaxy, Messier 82.

    The most violent star-forming galaxies and nebulae are so hot they turn red, as ultraviolet radiation ionizes neutral hydrogen.

    4
    The great Orion Nebula is a fantastic example of an emission nebula, as evidenced by its red hues and its characteristic emission at 656.3 nanometers. Image credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team.

    5
    This image from ESO’s Very Large Telescope shows the glowing green planetary nebula IC 1295 surrounding a dim and dying star located about 3300 light-years away. Image credit: ESO / FORS instrument.

    But there’s another, green line that happens only when oxygen gets doubly ionized at the hottest temperatures of all: 50,000 K and above.

    6
    Modern ‘green pea’ galaxies have their doubly-ionized oxygen emission offset from the main galaxy; in the Subaru Deep Field, the galaxies themselves exhibit the strong emission. Image credit: NASA, ESA, and Z. Levay (STScI), with science by NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa).

    Only planetary nebulae, with super-hot young white dwarfs, and the ultra-rare “green pea” galaxies exhibit these features.

    7
    The Subaru Deep Field, containing thousands of distant galaxies exhibiting these oxygen lines. Image credit: Subaru telescope, National Astronomical Observatory of Japan (NAOJ); Image processing: R. Jay GaBany.

    But by looking at the most active star-forming galaxies in the Subaru Deep Field (above), Matthew Malkan and Daniel Cohen found, that all galaxies from 11 billion years ago or more emit this green signature.

    8
    The strong green emission line (highest point) as shown in a sample of over 1,000 galaxies, spectrally stacked from the Subaru Deep Field. The other point “above” the curves is from hydrogen; the strong green oxygen line indicates incredibly intense radiation. Image credit: Malkan and Cohen (2017).

    The unexpected brightness and hotness of these galaxies hints that the stars in the ultra-distant Universe are somehow hotter than the hottest stars today.

    9
    The merging star clusters at the heart of the Tarantula Nebula, which contains the hottest stars in the local group, are still below 50,000 K. Perhaps lower metallicities, higher masses, or even a top-heavy initial mass function among stars in the early Universe are responsible for the increased, high temperatures. Image credit: NASA, ESA, and E. Sabbi (ESA/STScI); Acknowledgment: R. O’Connell (University of Virginia) and the Wide Field Camera 3 Science Oversight Committee.

    10
    The reionization and star-formation history of our Universe. The study hints that green, oxygen-rich galaxies may have been responsible for reionization. Image credit: NASA / S.G. Djorgovski & Digital Media Center / Caltech.

    JWST, launching 2018, will find out for sure.

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 1:56 pm on January 16, 2017 Permalink | Reply
    Tags: Astronomy, , FO Aquarii, , Sarah L. Krizmanich Telescope   

    From Notre Dame: “Notre Dame astrophysicists discover dimming of binary star’ 

    Notre Dame bloc

    Notre Dame University

    January 16, 2017
    Brian Wallheimer

    A team of University of Notre Dame astrophysicists led by Peter Garnavich, professor of physics, has observed the unexplained fading of an interacting binary star, one of the first discoveries using the University’s Sarah L. Krizmanich Telescope.

    Notre Dame Rooftop Sarah L Krizmanich  Telescope
    Notre Dame Rooftop Sarah L Krizmanich  Telescope Interior
    Notre Dame Rooftop Sarah L Krizmanich Telescope

    The binary star, FO Aquarii, located in the Milky Way galaxy and Aquarius constellation about 500 light-years from Earth, consists of a white dwarf and a companion star donating gas to the compact dwarf, a type of binary system known as an intermediate polar. The system is bright enough to be observed with small telescopes. Garnavich and his team started studying FO Aquarii, known as “king of the intermediate polars,” a few years ago when NASA’s Kepler Telescope was pointed toward it for three months. The star rotates every 20 minutes, and Garnavich wanted to investigate whether the period was changing.

    “I asked Erin Aadland, an REU student, to precisely measure the spin rate of a white dwarf. Does it speed up or slow down?” he said. “We can do that by looking at the interval between flashes from the star just like we use the ticks in a clock to tell time. The star turned out to have other plans for the summer.”

    Intermediate polars are interesting binary systems because the low-density star drops gas toward the compact dwarf, which catches the matter using its strong magnetic field and funnels it to the surface, a process called accretion. The gas emits X-rays and optical light as it falls, and we see regular light variations as the stars orbit and spin. Graduate student Mark Kennedy studied the light variations in detail during the three months the Kepler Space Telescope was pointing at FO Aquarii in 2014. Kennedy is a Naughton Fellow from University College, Cork, in Ireland who spent a year and a half working at Notre Dame on interacting binary stars. “Kepler observed FO Aquarii every minute for three months, and Mark’s analysis of the data made us think we knew all we could know about this star,” Garnavich said.

    Once Kepler was pointed in a new direction, Garnavich and his group used the Krizmanich Telescope to continue the study.

    “Just after the star came around the sun last year, we started looking at it through the Krizmanich Telescope, and we were shocked to see it was seven times fainter than it had ever been before,” said Colin Littlefield, a member of the Garnavich lab. “The dimming is a sign that the donating star stopped sending matter to the compact dwarf, and it’s unclear why. Although the star is becoming brighter again, the recovery to normal brightness has been slow, taking over six months to get back to where it was when Kepler observed.”

    “Normally, the light that we’d see would come from the accretion energy, and it got a lot weaker when the gas flow stopped. We are now following the recovery over months,” Garnavich said.

    One theory is that a star spot, a cool region on the companion, rotated into just the right position to disrupt the flow of hydrogen from the donating star. But that doesn’t explain why the star hasn’t then recovered as quickly as it dimmed.

    Garnavich and his team also found that the light variations of FO Aquarii became very complex during its low state. The low gas transfer rate had meant the dominant, 20-minute signal had faded and allowed other periods to show up. Instead of a steady 20 minutes between flashes, sometimes there was an 11-minute signal and at other times a 21-minute pulse.

    “We had never seen anything like this before,” Garnavich said. “For two hours, it would flash quickly and then the next two hours it would pulse more slowly.”

    The Sarah L. Krizmanich Telescope, installed on the roof of the Jordan Hall of Science in 2013, features a 0.8-meter (32-inch diameter) mirror. It provides undergraduate and graduate students cutting-edge technology for research and is used to test new instrumentation developed in the Department of Physics at Notre Dame.

    The Notre Dame team that studied FO Aquarii included Littlefield, Aadland and Kennedy. The team’s findings have been published in the Astrophysical Journal. Institutions that contributed to the work include The Ohio State University, University Cote d’Azur (France), University de Liege (Belgium) and the American Association of Variable Star Observers (AAVSO)

    See the full article here .

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    Notre Dame Campus

    The University of Notre Dame du Lac (or simply Notre Dame /ˌnoʊtərˈdeɪm/ NOH-tər-DAYM) is a Catholic research university located near South Bend, Indiana, in the United States. In French, Notre Dame du Lac means “Our Lady of the Lake” and refers to the university’s patron saint, the Virgin Mary.

    The school was founded by Father Edward Sorin, CSC, who was also its first president. Today, many Holy Cross priests continue to work for the university, including as its president. It was established as an all-male institution on November 26, 1842, on land donated by the Bishop of Vincennes. The university first enrolled women undergraduates in 1972. As of 2013 about 48 percent of the student body was female.[6] Notre Dame’s Catholic character is reflected in its explicit commitment to the Catholic faith, numerous ministries funded by the school, and the architecture around campus. The university is consistently ranked one of the top universities in the United States and as a major global university.

    The university today is organized into five colleges and one professional school, and its graduate program has 15 master’s and 26 doctoral degree programs.[7][8] Over 80% of the university’s 8,000 undergraduates live on campus in one of 29 single-sex residence halls, each of which fields teams for more than a dozen intramural sports, and the university counts approximately 120,000 alumni.[9]

    The university is globally recognized for its Notre Dame School of Architecture, a faculty that teaches (pre-modernist) traditional and classical architecture and urban planning (e.g. following the principles of New Urbanism and New Classical Architecture).[10] It also awards the renowned annual Driehaus Architecture Prize.

     
  • richardmitnick 1:05 pm on January 16, 2017 Permalink | Reply
    Tags: , Astronomy, , , , , ,   

    From Motherboard: “An Earth-Sized Telescope is About to ‘See’ a Black Hole For the First Time” 

    motherboard

    Motherboard

    January 13, 2017
    William Rauscher

    We were perched dizzyingly high in the Chilean Andes, ringed by a herd of sixty-six white giants. Through the broad windows of the low, nondescript building in which we stood, we could see massive white radio antennas outside against the Martian-red soil of the desolate Chajnantor Plateau, their dishes thrust towards a pure blue sky.

    This is the Atacama Large Millimeter Array, also known as ALMA—one of the world’s largest radio telescope arrays, an international partnership that spans four continents. In spring of 2017, ALMA, along with eight other telescopes around the world, will aim towards the center of the Milky Way, around 25,000 light years from Earth, in an attempt to capture the first-ever image of a black hole. This is part of a daring astronomy project called the Event Horizon Telescope (EHT).

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    My partner Dave Robertson and I took turns huffing from a can of oxygen to stave off the altitude sickness that can come on at 16,500 feet. Our guide Danilo Vidal, an energetic Chilean who wore his dark hair in a ponytail, pointed to a grey metal door with a glass window. “If we open that door,” said Vidal, “everyone in science will hate us for the rest of our lives.” Confused by this cryptic statement, I took another hit from the oxygen and peered through the glass, into the heart of the experiment.

    Among a small forest of processors, I could see an eggshell-white box that resembled a dorm room refrigerator. Inside was the brand-new maser, an ultraprecise atomic clock that syncs up every antenna on-site, and then syncs ALMA itself to the Event Horizon Telescope’s global network, lending so much dish-space and processing power that it effectively doubles the entire network’s resolution.

    1
    Christophe Jacques of the NRAO inspects the wiring on ALMA’s new hydrogen maser atomic clock during installation. Image: Carlos Padilla/NRAO/AUI/NSF

    To keep equipment from overheating, the room is kept at an absurdly low temperature—very close to absolute zero. If we opened the door, Vidal explained, emergency systems would instantly shut down the maser to protect it, and ALMA’s beating heart would stop, ruining multiple international astronomy projects, including the EHT.

    Claudio Follert, an ALMA fiber-optic specialist in his mid-fifties, was there in 2014 when the maser first arrived—he told me it was a machine he had never seen before, carried in by strange men. The men were sent by the EHT, which is based out of MIT.

    The EHT is made possible by the maser’s astonishing precision—about one billion times more precise than the clock in your smartphone.

    Designed by an international team led by MIT scientist Shep Doeleman, the EHT is the first of its kind-a global telescope network that uses a technique called interferometry to synthesize astronomical data from multiple sources, each with its own maser—including ALMA in Chile, the Large Millimeter Telescope atop the Sierra Negra volcano in Mexico, and the National Radio Astronomy Observatory in Virginia.

    Together, these telescopes create a super-telescope that is quite literally the size of the Earth, with enough resolution to photograph an orange on the Moon.

    With ALMA recently added to this Avengers-like team of radio telescopes, the network is ten times more sensitive. As a result, Doeleman’s group believes it has the firepower to penetrate the interstellar gases that cloak their targets: supermassive black holes. Drawn into orbit by the black holes’ gravity, these gases form gargantuan clouds that yield nothing to optical telescopes.

    Faint radio signals from the black holes, on the other hand, slip through the gas clouds and are ultimately detected on Earth.

    Black holes are the folk legends of outer space. Since no light can escape them, they’re invisible to the eye, and we have no confirmation that they actually exist—only heaps of indirect evidence, particularly the gravitational wobbles in orbits of nearby stars, the behavior of interstellar gas clouds, and the gaseous jets that spew into space when an unseen source of extreme gravity appears to rip cosmic matter to shreds.

    Black holes challenge our most fundamental beliefs about reality. Visionary scientific minds, including the theoretical physicists Stephen Hawking and Kip Thorne, have devoted entire books to unpacking the hallucinatory scenarios thought to be induced by black holes’ gravitational forces—imagine the bottom of your body violently wrenched away from the top, physically stretching you like a Looney Tunes character, a scenario that Thorne’s Black Holes and Time Warps paints in stomach-churning detail.

    2
    An image from the heart of the Milky Way from NASA’s Chandra X-ray Observatory. The supermassive black hole is at the center. Image: NASA/CXC/MIT/F. Baganoff et al.

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    Sag A*  NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way
    Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

    Black holes are thought to lurk at the centers of galaxies including our own. Prove the existence of Sagittarius A*, the supermassive black hole at the heart of the Milky Way, and you are one step closer to solving another mystery: the origin of humankind, and all life as we know it.

    “The black hole at the center of our galaxy has everything to do with our own origin,” said Violette Impellizzeri, an ALMA astronomer collaborating with Event Horizon Telescope. Supermassive black holes are thought to regulate the stars that surround them, influencing their formation and orbit. “Understanding how our galaxy was formed leads to our own origin directly,” she said.

    Scientists estimate the mass of Sagittarius A* to be four million times that of our Sun, yet its diameter is roughly equal to the distance from our sun to Mercury—not much, in cosmic terms. The resulting density produces gravity so strong that space and time distort around it, making it invisible.

    The current theory, espoused by Thorne, is that the distance from the center of a black hole, known as the singularity, to its edge, known as the event horizon, becomes so warped that it nears infinite length, and light simply runs out of energy as it tries to escape.

    It took Doeleman, the project leader at MIT, to decide that in order to see the unseeable, you would first have to create a new kind of vision. With ALMA as part of the giant EHT network, we can take a radio “photograph” of the matter that orbits Sagittarius A*—called the accretion disk—and finally see the black hole in shadow: its first-ever portrait.

    • Vidal and Follert, the guide and fiber-optic specialist, led us out onto the plateaus. There was work to do: one of the antennas was hobbled by a damaged radio receptor.

    It was blindingly bright and windy, not to mention dry—Chajnantor is located in Chile’s Atacama Desert, the driest place on Earth, if you don’t count the poles. Completely inhospitable for human beings, Chajnantor is an ideal setting for a radio telescope: the elevation puts it closer to the stars, and the strikingly low water vapor keeps the cosmic signals pristine.

    For some, like ALMA’s crew, as well as Doeleman, the extreme environment is part of the attraction. “I just love getting to the telescopes,” he said. At 50, Doeleman is fresh-faced, with glasses and thinning hair that make him look every part the bookish scientist. His outgoing personality and entrepreneurial vigor reflect an explorer’s spirit more at home in the field than behind a desk.

    Doeleman regularly travels to each EHT site around the world, many of them located in extreme environments like the Andes or the Sierra Negra. “The adventure part is what motivates me—driving along dirt roads, up the sides of mountains, to install new instruments, doing observations that have never been done before. It’s a little bit like Jacques Cousteau—we’re not sitting in armchairs in our offices.”

    Outside on Chajnantor, I felt light-headed. I tried to keep my breathing steady: low oxygen can quickly wreck your mental faculties. On the plateau, Dave and I were dwarfed by ALMA’s antennas, which blocked out the desert sun. They felt powerful and eerie, like Easter Island statues. Even when standing directly beneath these behemoths, it wasn’t clear how they were controlled—the white dishes seemed to twist and pivot without warning.

    3
    Using a technique called interferometry, ALMA’s antennas can be configured to act as one giant antenna, and ALMA itself can be synced up with telescopes worldwide. Image: Dave Robertson

    An ALMA antenna is useless when one of its radio receptors is out of tune. We followed Follert up several steel ladders, boots clanging on metal, until we were in a low-ceilinged maintenance room inside one of the antennas. We helped him remove the damaged receptor, a long metal cylinder resembling a futuristic bazooka.

    Vidal drove us back down the mountain to the Operations Support Facility (OSF), ALMA’s headquarters, so we could see the lab where receptors are maintained.

    Per strict international regulations, Vidal was required to breathe through an oxygen tube as he drove, lest the high altitude cause him to lose consciousness behind the wheel.

    As we descended, Vidal radioed at regular intervals to identify our location. All around us the mountain slopes were red, rocky and barren—no wonder that NASA regularly deploys expeditions to this desert to replicate conditions on Mars.

    Located at 9,000 ft, the OSF is where ALMA’s staff call home: a total of 600 scientists working in shifts are based here, including engineers and technicians, from over 20 countries. The working conditions can be extreme. Staff hole up in weeklong shifts separated from friends and family, and endure the short and long-term health risks of high elevation, including a stroke or pulmonary edema, where fluid fills your lungs and you suffocate.

    It is thus maybe not surprising to find out that the entire staff are monitored regularly by medical personnel, and that emergency oxygen and a hyperbaric chamber are on-hand.

    They unwind by exercising and watching movies, although certain sci-fi flicks are frowned upon. “We need a break from space sometimes,” said Follert. Alcohol consumption on site is strictly forbidden—have even a tipple and you risk amplifying the physical effects of high elevation.

    4
    Aerial picture of ALMA’s Operations Support Facility. Image: Carlos Padilla/NRAO/AUI/NSF

    The close teamwork at ALMA is absolutely essential for the life of the observatory. Detecting cosmic radio signals, including those sent from a black hole, requires constant cooperation across teams, who must obsessively calibrate, maintain and repair their instruments to fend off unwanted noise.

    ALMA and the other telescopes on the EHT will soon turn towards the center of the Milky Way to tune in to the black hole’s narrow radio frequency. The data that ALMA collects will be so large, it cannot be transferred online. Instead, physical hard drives will shipped by “sneakernet”: loaded into the belly of a 747 and flown directly to MIT.

    When ALMA’s data is correlated with the other telescopes later this year, Sagittarius A* should appear against the glowing gas of the accretion disk. Maybe.

    Actually, said Doeleman, “we don’t know what we’re going to see. Nature can be cruel. We may see something boring. But we’re not married to one outcome—we’re going to see nature the way nature is.”

    See the full article here .

    The full EHT:

    Event Horizon Telescope Array

    Event Horizon Telescope map

    The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope sites, via University of Arizona at https://www.as.arizona.edu/event-horizon-telescope.

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment (APEX)

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    Future Array/Telescopes

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

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    The future is wonderful, the future is terrifying. We should know, we live there. Whether on the ground or on the web, Motherboard travels the world to uncover the tech and science stories that define what’s coming next for this quickly-evolving planet of ours.

    Motherboard is a multi-platform, multimedia publication, relying on longform reporting, in-depth blogging, and video and film production to ensure every story is presented in its most gripping and relatable format. Beyond that, we are dedicated to bringing our audience honest portraits of the futures we face, so you can be better informed in your decision-making today.

     
    • Jim Ruebush 1:51 pm on January 16, 2017 Permalink | Reply

      Very interesting. I look forward to seeing results. The radio telescopes at Atacama are the subject of a blog post of mine a few years ago. http://bit.ly/2jpp7hl

      Only 2 miles from my home in Iowa is a radio telescope part of the VLBA. I’ve been fortunate to go up inside and stand in the dish. What fun.

      Keep up the good work and posts.

      Like

  • richardmitnick 12:06 pm on January 16, 2017 Permalink | Reply
    Tags: ASKAP finally hits the big-data highway, Astronomy, , , , , , , WALLABY - Widefield ASKAP L-band Legacy All-sky Blind surveY   

    From The Conversation for SKA: “The Australian Square Kilometre Array Pathfinder finally hits the big-data highway” 

    Conversation
    The Conversation

    SKA Square Kilometer Array

    SKA

    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia
    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

    January 15, 2017
    Douglas Bock
    Director of Astronomy and Space Science, CSIRO

    Antony Schinckel
    ASKAP Director, CSIRO

    You know how long it takes to pack the car to go on holidays. But there’s a moment when you’re all in, everyone has their seatbelt on, you pull out of the drive and you’re off.

    Our ASKAP (Australian Square Kilometre Array Pathfinder) telescope has just pulled out of the drive, so to speak, at its base in Western Australia at the Murchison Radio-astronomy Observatory (MRO), about 315km northeast of Geraldton.

    ASKAP is made of 36 identical 12-metre wide dish antennas that all work together, 12 of which are currently in operation. Thirty ASKAP antennas have now been fitted with specialised phased array feeds, the rest will be installed later in 2017.

    Until now, we’d been taking data mainly to test how ASKAP performs. Having shown the telescope’s technical excellence it’s now off on its big trip, starting to make observations for the big science projects it’ll be doing for the next five years.

    And it’s taking lots of data. Its antennas are now churning out 5.2 terabytes of data per second (about 15 per cent of the internet’s current data rate).

    Once out of the telescope, the data is going through a new, almost automatic data-processing system we’ve developed.

    It’s like a bread-making machine: put in the data, make some choices, press the button and leave it overnight. In the morning you have a nice batch of freshly made images from the telescope.

    Go the WALLABIES

    The first project we’ve been taking data for is one of ASKAP’s largest surveys, WALLABY (Widefield ASKAP L-band Legacy All-sky Blind surveY).

    On board the survey are a happy band of 100-plus scientists – affectionately known as the WALLABIES – from many countries, led by one of our astronomers, Bärbel Koribalski, and Lister Staveley-Smith of the International Centre for Radio Astronomy Research (ICRAR), University of Western Australia.

    They’re aiming to detect and measure neutral hydrogen gas in galaxies over three-quarters of the sky. To see the farthest of these galaxies they’ll be looking three billion years back into the universe’s past, with a redshift of 0.26.

    2
    Neutral hydrogen gas in one of the galaxies, IC 5201 in the southern constellation of Grus (The Crane), imaged in early observations for the WALLABY project. Matthew Whiting, Karen Lee-Waddell and Bärbel Koribalski (all CSIRO); WALLABY team, Author provided

    Neutral hydrogen – just lonely individual hydrogen atoms floating around – is the basic form of matter in the universe. Galaxies are made up of stars but also dark matter, dust and gas – mostly hydrogen. Some of the hydrogen turns into stars.

    Although the universe has been busy making stars for most of its 13.7-billion-year life, there’s still a fair bit of neutral hydrogen around. In the nearby (low-redshift) universe, most of it hangs out in galaxies. So mapping the neutral hydrogen is a useful way to map the galaxies, which isn’t always easy to do with just starlight.

    But as well as mapping where the galaxies are, we want to know how they live their lives, get on with their neighbours, grow and change over time.

    When galaxies live together in big groups and clusters they steal gas from each other, a processes called accretion and stripping. Seeing how the hydrogen gas is disturbed or missing tells us what the galaxies have been up to.

    We can also use the hydrogen signal to work out a lot of a galaxy’s individual characteristics, such as its distance, how much gas it contains, its total mass, and how much dark matter it contains.

    This information is often used in combination with characteristics we learn from studying the light of the galaxy’s stars.

    Oh what big eyes you have ASKAP

    ASKAP sees large pieces of sky with a field of view of 30 square degrees. The WALLABY team will observe 1,200 of these fields. Each field contains about 500 galaxies detectable in neutral hydrogen, giving a total of 600,000 galaxies.

    3
    One of the first fields targeted by WALLABY, the NGC 7232 galaxy group. Ian Heywood (CSIRO); WALLABY team, Author provided

    This image (above) of the NGC 7232 galaxy group was made with just two nights’ worth of data.

    ASKAP has now made 150 hours of observations of this field, which has been found to contain 2,300 radio sources (the white dots), almost all of them galaxies.

    It has also observed a second field, one containing the Fornax cluster of galaxies, and started on two more fields over the Christmas and New Year period.

    Even more will be dug up by targeted searches. Simply detecting all the WALLABY galaxies will take more than two years, and interpreting the data even longer. ASKAP’s data will live in a huge archive that astronomers will sift through over many years with the help of supercomputers at the Pawsey Centre in Perth, Western Australia.

    ASKAP has nine other big survey projects planned, so this is just the beginning of the journey. It’s really a very exciting time for ASKAP and the more than 350 international scientists who’ll be working with it.

    Who knows where this Big Trip will take them, and what they’ll find along the way?

    See the full article here .

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    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 11:32 am on January 16, 2017 Permalink | Reply
    Tags: A slice of Sagittarius, Astronomy, , NASA/ESA Hubble ACS   

    From Hubble: “A slice of Sagittarius” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    1
    Credit: NASA/ESA Hubble

    16 January 2017
    No writer credit found

    This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer).

    NASA/ESA Hubble ACS

    The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colours of the stars, and the dramatic crosses that burst from the centres of the brightest bodies.

    While some of the colours in this frame have been enhanced and tweaked during the process of creating the image from the observational data, different stars do indeed glow in different colours. Stars differ in colour according to their surface temperature: very hot stars are blue or white, while cooler stars are redder. They may be cooler because they are smaller, or because they are very old and have entered the red giant phase, when an old star expands and cools dramatically as its core collapses.
    The crosses are nothing to do with the stars themselves, and, because Hubble orbits above Earth’s atmosphere, nor are they due to any kind of atmospheric disturbance. They are actually known as diffraction spikes, and are caused by the structure of the telescope itself. Like all big modern telescopes, Hubble uses mirrors to capture light and form images. Its secondary mirror is supported by struts, called telescope spiders, arranged in a cross formation, and they diffract the incoming light. Diffraction is the slight bending of light as it passes near the edge of an object. Every cross in this image is due to a single set of struts within Hubble itself! Whilst the spikes are technically an inaccuracy, many astrophotographers choose to emphasise and celebrate them as a beautiful feature of their images.

    See the full 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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    AURA Icon

    NASA image

     
  • richardmitnick 10:39 am on January 16, 2017 Permalink | Reply
    Tags: Astronomy, , , , There are at least two trillion galaxies in the universe ten times more than previously thought,   

    From U Nottingham: “There are at least two trillion galaxies in the universe, ten times more than previously thought” 

    1

    University of Nottingham

    13 Oct 2016 [Just turned up in a social media search]
    Lindsay Brooke
    Media Relations Manager
    lindsay.brooke@nottingham.ac.uk
    +44 (0)115 951 5751
    Location: University Park

    1
    Image of the HST GOODS-South field, one of the deepest images of the sky but covering just one millionth of its total area. The new estimate for the number of galaxies is ten times higher than the number seen in this image. Credit: NASA / ESA / The GOODS Team / M. Giavalisco (UMass., Amherst)

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Astronomers have long sought to determine how many galaxies there are in the universe. This is a fundamental question that we have only been able to address with any certainty due to new scientific results.

    During the past 20 years very deep Hubble Space Telescope images have found a myriad of faint galaxies, and it was approximated that the observable Universe contains about 100 billion galaxies in total.

    Now, an international team, led by Christopher Conselice, Professor of Astrophysics at The University of Nottingham, has shown that the actual number is much higher than this.

    Professor Conselice and his team has shown that the number of galaxies in our universe is at least two trillion – ten times more than previously thought – the often quoted value of around 100 Billion.

    Current astronomical technology allows us to study a fraction of these galaxies– just 10%.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    It means that over 90% of the galaxies in our universe have yet to be discovered, and will only be seen once bigger and better telescopes are developed.

    ESO 50 Large
    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile
    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile

    LSST
    LSST/Camera, built at SLAC
    LSST/Camera, built at SLAC
    LSST Interior
    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.
    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes

    TMT-Thirty Meter Telescope, proposed for Mauna Kea, Hawaii, USA
    TMT-Thirty Meter Telescope, proposed for Mauna Kea, Hawaii, USA

    Giant Magellan Telescope, Las Campanas Observatory, to be built  some 115 km (71 mi) north-northeast of La Serena, Chile
    Giant Magellan Telescope, Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    NASA/WFIRST telescope
    NASA/WFIRST telescope

    The research – The Evolution of Galaxy number density at Z < 8 and its implications – is published today (October 13, 2016) in the Astrophysical Journal – the foremost research journal in the world dedicated to recent developments, discoveries and theories about astronomy and astrophysics.

    The results have clear implications for galaxy formation, and also help solve an ancient astronomical paradox — why is the sky dark at night?

    Professor Conselice said: “We are missing the vast majority of galaxies because they are very faint and far away. The number of galaxies in the universe is a fundamental number we would like to know, and it boggles the mind that over 90% of the galaxies in the universe have yet to be studied.

    Who knows what interesting properties we will find when we study these galaxies with the next generation of telescopes. These galaxies will likely hold the clues to many outstanding astrophysical issues.”

    Intergalactic archaeological dig

    Professor Conselice’s research is the culmination of 15 year’s work. His team converted pencil beam images of deep space from telescopes around the world, and especially from the Hubble telescope into 3D maps to calculate the volume as well as the density of galaxies of one tiny bit of space after another.

    This painstaking research enabled him to establish how many galaxies we have missed – much like an intergalactic archaeological dig.

    The results of this study are based on the measurements of the number of galaxies at different epochs – different instances in time – through the universe’s history.

    When Professor Conselice and his team at Nottingham, in collaboration with scientists from the Leiden Observatory at Leiden University in the Netherlands and the Institute for Astronomy at the University of Edinburgh, examined how many galaxies there were in a given value they found that this increased significantly at earlier times.

    In fact, it appears that there are a factor of 10 more galaxies in a given volume of space when the universe was a few billion years old compared with today. Most of these galaxies are low mass systems with masses similar to those of the satellite galaxies surrounding the Milky Way.

    Professor Conselice said: “This is very surprising as we know that over the 13.7 billion years of cosmic evolution galaxies are growing through star formation and merging with other galaxies. Thus, to find that there were in fact more galaxies in the past implies that that significant evolution in galaxies must have occurred to reduce the number of galaxies through extensive merging of systems. This also gives us a verification of the top-down formation of structure in the universe.”

    Probing cosmic history answers astronomical questions

    By probing deep into space Professor Conselice and his team have been able to go way back in time – more than 13 billion years in the past – to find out how our universe evolved and answer some vexing questions.

    The implications of this research are many, for instance; galaxies are likely to be forming by merging together. This decreases the number of systems as time progresses which provides a possible solution to Oblers’ paradox – why the sky is dark at night?

    Solutions to this in the past were based on the fact that the universe is finite in size as well as in time. However, if we consider all the undiscovered galaxies then in principle the critiera for Oblers’ paradox is met.

    However, most galaxies in the universe are very distant and their light is absorbed by gas in intergalactic space. Otherwise, we would see the night sky lit up everywhere.

    See the full article here .

    Please help promote STEM in your local schools.

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    “The University of Nottingham shares many of the characteristics of the world’s great universities. However, we are distinct not only in our key strengths but in how our many strengths combine: we are financially secure, campus based and comprehensive; we are research-led and recruit top students and staff from around the world; we are committed to internationalising all our core activities so our students can have a valuable and enjoyable experience that prepares them well for the rest of their intellectual, professional and personal lives.”

     
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