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  • richardmitnick 9:47 am on June 13, 2018 Permalink | Reply
    Tags: ALMA, ALMA Discovers Trio of Infant Planets around Newborn Star, , , , , ,   

    From ALMA: “ALMA Discovers Trio of Infant Planets around Newborn Star” 

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

    From ALMA

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    13 June 2018
    Christophe Pinte
    Monash University
    Clayton, Victoria, Australia
    Tel: +61 4 90 30 24 18
    Email: christophe.pinte@univ-grenoble-alpes.fr

    Richard Teague
    University of Michigan
    Ann Arbor, Michigan, USA
    Tel: +1 734 764 3440
    Email: rteague@umich.edu

    Calum Turner
    ESO Assistant Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6670
    Email: calum.turner@eso.org

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

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

    1
    ALMA has uncovered convincing evidence that three young planets are in orbit around the infant star HD 163296. Using a novel planet-finding technique, astronomers have identified three discrete disturbances in the young star’s gas-filled disc: the strongest evidence yet that newly formed planets are in orbit there. These are considered the first planets discovered with ALMA. This image shows part of the ALMA data set at one wavelength and reveals a clear “kink” in the material, which indicates unambiguously the presence of one of the planets. Credit: ESO, ALMA (ESO/NAOJ/NRAO); Pinte et al.

    Two independent teams of astronomers have used ALMA to uncover convincing evidence that three young planets are in orbit around the infant star HD 163296. Using a novel planet-finding technique, the astronomers identified three disturbances in the gas-filled disc around the young star: the strongest evidence yet that newly formed planets are in orbit there. These are considered the first planets to be discovered with ALMA.

    6
    Artist impression of protoplanets forming around a young star. Credit: NRAO/AUI/NSF; S. Dagnello

    The Atacama Large Millimeter/submillimeter Array (ALMA) has transformed our understanding of protoplanetary discs — the gas- and dust-filled planet factories that encircle young stars. The rings and gaps in these discs provide intriguing circumstantial evidence for the presence of protoplanets [1]. Other phenomena, however, could also account for these tantalising features.

    3
    This wide-field image shows the surroundings of the young star HD 163296 in the rich constellation of Sagittarius (The Archer). This picture was created from the material forming part of the Digitized Sky Survey 2. HD 163296 is the bright bluish star at the center. Credit: ESO/Digitized Sky Survey 2; Acknowledgement: Davide De Martin.

    But now, using a novel planet-hunting technique that identifies unusual patterns in the flow of gas within a planet-forming disc around a young star, two teams of astronomers have each confirmed distinct, telltale hallmarks of newly formed planets orbiting an infant star [2].

    “Measuring the flow of gas within a protoplanetary disc gives us much more certainty that planets are present around a young star,” said Christophe Pinte of Monash University in Australia and Institut de Planétologie et d’Astrophysique de Grenoble (Université de Grenoble-Alpes/CNRS) in France, and lead author on one of the two papers. “This technique offers a promising new direction to understand how planetary systems form.”

    To make their respective discoveries, each team analysed ALMA observations of HD 163296, a young star about 330 light-years from Earth in the constellation of Sagittarius (The Archer) [3]. This star is about twice the mass of the Sun but is just four million years old — just a thousandth of the age of the Sun.

    “We looked at the localised, small-scale motion of gas in the star’s protoplanetary disc. This entirely new approach could uncover some of the youngest planets in our galaxy, all thanks to the high-resolution images from ALMA,” said Richard Teague, an astronomer at the University of Michigan and principal author on the other paper.

    Rather than focusing on the dust within the disc, which was clearly imaged in earlier ALMA observations, the astronomers instead studied carbon monoxide (CO) gas spread throughout the disc. Molecules of CO emit a very distinctive millimetre-wavelength light that ALMA can observe in great detail. Subtle changes in the wavelength of this light due to the Doppler effect reveal the motions of the gas in the disc.

    4
    The gaps between the rings are likely due to a depletion of dust and in the middle and outer gaps astronomers also found a lower level of gas. The depletion of both dust and gas suggests the presence of newly formed planets, each around the mass of Saturn, carving out these gaps on their brand new orbits. Credit: ESO, ALMA (ESO/NAOJ/NRAO); A. Isella; B. Saxton (NRAO/AUI/NSF).

    The team led by Teague identified two planets located approximately 12 billion and 21 billion kilometres from the star. The other team, led by Pinte, identified a planet at about 39 billion kilometres from the star [4].

    The two teams used variations on the same technique, which looks for anomalies in the flow of gas — as evidenced by the shifting wavelengths of the CO emission — that indicate the gas is interacting with a massive object [5].

    The technique used by Teague, which derived averaged variations in the flow of the gas as small as a few percent, revealed the impact of multiple planets on the gas motions nearer to the star. The technique used by Pinte, which more directly measured the flow of the gas, is better suited to studying the outer portion of the disc. It allowed the authors to more accurately locate the third planet, but is restricted to larger deviations of the flow, greater than about 10%.

    In both cases, the researchers identified areas where the flow of the gas did not match its surroundings — a bit like eddies around a rock in a river. By carefully analysing this motion, they could clearly see the influence of planetary bodies similar in mass to Jupiter.

    This new technique allows astronomers to more precisely estimate protoplanetary masses and is less likely to produce false positives. “We are now bringing ALMA front and centre into the realm of planet detection,” said coauthor Ted Bergin of the University of Michigan.

    Both teams will continue refining this method and will apply it to other discs, where they hope to better understand how atmospheres are formed and which elements and molecules are delivered to a planet at its birth.


    Zooming in on the young star HD 163296 from ALMA Observatory

    Notes

    [1] Although thousands of exoplanets have been discovered in the last two decades, detecting protoplanets remains at the cutting edge of science and there have been no unambiguous detections before now. The techniques currently used for finding exoplanets in fully formed planetary systems — such as measuring the wobble of a star or the dimming of starlight due to a transiting planet — do not lend themselves to detecting protoplanets.

    [2] The motion of gas around a star in the absence of planets has a very simple, predictable pattern (Keplerian rotation) that is nearly impossible to alter both coherently and locally, so that only the presence of a relatively massive object can create such disturbances.

    [3] ALMA’s stunning images of HD 163296 and other similar systems have revealed intriguing patterns of concentric rings and gaps within protoplanetary discs. These gaps may be evidence that protoplanets are ploughing the dust and gas away from their orbits, incorporating some of it into their own atmospheres. A previous study [Physical Review Letters] of this particular star’s disc shows that the gaps in the dust and gas overlap, suggesting that at least two planets have formed there.

    These initial observations, however, merely provided circumstantial evidence and could not be used to accurately estimate the masses of the planets.

    [4] These correspond to 80, 140 and 260 times the distance from the Earth to the Sun.

    [5] This technique is similar to the one that led to the discovery of the planet Neptune in the nineteenth century. In that case anomalies in the motion of the planet Uranus were traced to the gravitational effect of an unknown body, which was subsequently discovered visually in 1846 and found to be the eighth planet in the Solar System.
    More information

    This research was presented in two papers to appear in the same edition of the Astrophysical Journal Letters. The first is entitled Kinematic evidence for an embedded protoplanet in a circumstellar disc, by C. Pinte et al. and the second A Kinematic Detection of Two Unseen Jupiter Mass Embedded Protoplanets, by R. Teague et al.

    The Pinte team is composed of: C. Pinte (Monash University, Clayton, Victoria, Australia; Univ. Grenoble Alpes, CNRS, IPAG, Grenoble, France), D. J. Price (Monash University, Clayton, Victoria, Australia), F. Ménard (Univ. Grenoble Alpes, CNRS, IPAG, Grenoble, France), G. Duchêne (University of California, Berkeley California, USA; Univ. Grenoble Alpes, CNRS, IPAG, Grenoble, France), W.R.F. Dent (Joint ALMA Observatory, Santiago, Chile), T. Hill (Joint ALMA Observatory, Santiago, Chile), I. de Gregorio-Monsalvo (Joint ALMA Observatory, Santiago, Chile), A. Hales (Joint ALMA Observatory, Santiago, Chile; National Radio Astronomy Observatory, Charlottesville, Virginia, USA) and D. Mentiplay (Monash University, Clayton, Victoria, Australia).

    The Teague team is composed of: Richard D. Teague (University of Michigan, Ann Arbor, Michigan, USA), Jaehan Bae (Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC, USA), Edwin A. Bergin (University of Michigan, Ann Arbor, Michigan, USA), Tilman Birnstiel (University Observatory, Ludwig-Maximilians-Universität München, Munich, Germany) and Daniel Foreman- Mackey (Center for Computational Astrophysics, Flatiron Institute, New York, USA).

    Research paper Pinte et al. in Astrophysical Journal Letters
    Research paper Teague et al. in Astrophysical Journal Letters

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition


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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
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    NAOJ

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  • richardmitnick 2:12 pm on June 4, 2018 Permalink | Reply
    Tags: "Too Many Massive Stars in Starburst Galaxies, ALMA, , , , , , , Near and Far"   

    From ALMA and VLT: “Too Many Massive Stars in Starburst Galaxies, Near and Far” 

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

    From ALMA

    and

    ESO 50 Large

    From European Southern Observatory

    4 June 2018

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Zhi-Yu Zhang
    University of Edinburgh and ESO
    Garching bei München, Germany
    Tel: +49-89-3200-6910
    Email: zzhang@eso.org

    Fabian Schneider
    Department of Physics — University of Oxford
    Oxford, United Kingdom
    Tel: +44-1865-283697
    Email: fabian.schneider@physics.ox.ac.uk

    Rob Ivison
    ESO
    Garching bei München, Germany
    Tel: +49-89-3200-6669
    Email: rob.ivison@eso.org

    Mariya Lyubenova
    ESO Outreach Astronomer
    Garching bei München, Germany
    Tel: +49 89 3200 6188
    Email: mlyubeno@eso.org

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

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

    1
    This artist’s impression shows a dusty galaxy in the distant Universe that is forming stars at a rate much higher than in our Milky Way. New ALMA observations have allowed scientists to lift the veil of dust and see what was previously inaccessible — that such starburst galaxies have an excess of massive stars as compared to more peaceful galaxies.
    Credit: ESO/M. Kornmesser

    2
    This image shows the four distant starburst galaxies observed by ALMA. The top images depict the 13CO emission from each galaxy, while the bottom ones show their C18O emission. The ratio of these two isotopologues allowed astronomers to determine that these starburst galaxies have an excess of massive stars. Credit: ALMA (ESO/NAOJ/NRAO), Zhang et al.


    Astronomers using ALMA and the VLT have discovered that starburst galaxies in both the early and the nearby Universe contain a much higher proportion of massive stars than is found in more peaceful galaxies. The video is available in 4K UHD. Credit: ESO.
    Directed by: Nico Bartmann.
    Editing: Nico Bartmann.
    Web and technical support: Mathias André and Raquel Yumi Shida.
    Written by: Stephen Molyneux and Richard Hook.
    Music: written and performed by Stan Dart (www.stan-dart.com).
    Footage and photos: ESO, M. Kornmesser, L. Calçada.
    Executive producer: Lars Lindberg Christensen.

    Astronomers using ALMA and the VLT have discovered that both starburst galaxies in the early Universe and a star-forming region in a nearby galaxy contain a much higher proportion of massive stars than is found in more peaceful galaxies. These findings challenge current ideas about how galaxies evolved, changing our understanding of cosmic star-formation history and the build up of chemical elements.

    Probing the distant Universe a team of scientists, led by University of Edinburgh astronomer Zhi-Yu Zhang, used the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate the proportion of massive stars in four distant gas-rich starburst galaxies [1]. These galaxies are seen when the Universe was much younger than it is now so the infant galaxies are unlikely to have undergone many previous episodes of star formation, which might otherwise have confused the results.

    Zhang and his team developed a new technique — analogous to radiocarbon dating (also known as carbon-14 dating) — to measure the abundances of different types of carbon monoxide in four very distant, dust-shrouded starburst galaxies [2]. They observed the ratio of two types of carbon monoxide containing different isotopes [3].

    “Carbon and oxygen isotopes have different origins”, explains Zhang. “18O is produced more in massive stars, and 13C is produced more in low- to intermediate-mass stars.” Thanks to the new technique the team was able to peer through the dust in these galaxies and assess for the first time the masses of their stars.

    The mass of a star is the most important factor determining how it will evolve. Massive stars shine brilliantly and have short lives and less massive ones, such as the Sun, shine more modestly for billions of years. Knowing the proportions of stars of different masses that are formed in galaxies therefore underpins astronomers’ understanding of the formation and evolution of galaxies throughout the history of the Universe. Consequently, it gives us crucial insights about the chemical elements available to form new stars and planets and, ultimately, the number of seed black holes that may coalesce to form the supermassive black holes that we see in the centres of many galaxies.

    Co-author Donatella Romano from the INAF-Astrophysics and Space Science Observatory in Bologna explains what the team found: “The ratio of 18O to 13C was about 10 times higher in these starburst galaxies in the early Universe than it is in galaxies such as the Milky Way, meaning that there is a much higher proportion of massive stars within these starburst galaxies.”

    The ALMA finding is corroborated by another discovery in the local Universe. A team led by Fabian Schneider of the University of Oxford, UK, made spectroscopic measurements with ESO’s Very Large Telescope of 800 stars in the gigantic star-forming region 30 Doradus in the Large Magellanic Cloud in order to investigate the overall distribution of stellar ages and initial masses [4].

    30 Doradus, The Tarantula Nebula or NGC 2070, resembles the legs of a tarantula 3 December 2009 ESO IDA Danish 1.5 m R. Gendler, C. C. Thöne, C. Féron, and J.-E. Ovaldsen

    Schneider explained, “We found around 30% more stars with masses more than 30 times that of the Sun than expected, and about 70% more than expected above 60 solar masses. Our results challenge the previously predicted 150 solar mass limit for the maximum birth mass of stars and even suggest that stars could have birth masses up to 300 solar masses!”

    Rob Ivison, co-author of the new ALMA paper, concludes: “Our findings lead us to question our understanding of cosmic history. Astronomers building models of the Universe must now go back to the drawing board, with yet more sophistication required.”
    Notes

    [1] Starburst galaxies are galaxies that are undergoing an episode of very intense star formation. The rate at which they form new stars can be 100 times or more the rate in our own galaxy, the Milky Way. Massive stars in these galaxies produce ionising radiation, stellar outflows, and supernova explosions, which significantly influence the dynamical and chemical evolution of the medium around them. Studying the mass distribution of stars in these galaxies can tell us more about their own evolution, and also the evolution of the Universe more generally.

    [2] The radiocarbon dating method is used for determining the age of an object containing organic material. By measuring the amount of 14C, which is a radioactive isotope whose abundance continuously decreases, one can calculate when the animal or plant died. The isotopes used in the ALMA study, 13C and 18O, are stable and their abundances continuously increase during the lifetime of a galaxy, being synthesised by thermal nuclear fusion reactions inside stars.

    [3] These different forms of the molecule are called isotopologues and they differ in the number of neutrons they can have. The carbon monoxide molecules used in this study are an example of such molecular species, because a stable carbon isotope can have either 12 or 13 nucleons in its nucleus, and a stable oxygen isotope can have either 16, 17, or 18 nucleons.

    [4] Schneider et al. made spectroscopic observations of individual stars in 30 Doradus, a star-forming region in the nearby Large Magellanic Cloud, using the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT).

    ESO/FLAMES on The VLT. FLAMES is the multi-object, intermediate and high resolution spectrograph of the VLT. Mounted at UT2, FLAMES can access targets over a field of view 25 arcmin in diameter. FLAMES feeds two different spectrograph covering the whole visual spectral range:GIRAFFE and UVES.

    Large Magellanic Cloud. Adrian Pingstone December 2003

    This study was one of the first to be carried out that has been detailed enough to show that the Universe is able to produce star-forming regions with different mass distributions from that in the Milky Way.

    7
    Galaxies in the distant Universe are seen during their youth and therefore have relatively short and uneventful star formation histories. This makes them an ideal laboratory to study the earliest epochs of star formation. But at a price — they are often enshrouded by obscuring dust that hampers the correct interpretation of the observations. Credit: ESO/M. Kornmesser

    8
    This kind of galaxy is typically forming stars at such a high rate that astronomers often refer to them as “starbursts”. They can form up to 1000 times more stars per year, compared to the Milky Way. Thanks to the unique capabilities of ALMA, astronomers have been able to measure the proportion of high-mass stars in such starburst galaxies. Credit: ESO/M. Kornmesser

    More information

    The ALMA results are published in a paper entitled Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time that will appear in Nature on 4 June 2018. The VLT results are published in a paper entitled An excess of massive stars in the local 30 Doradus starburst, which has been published in Science on 5 January 2018.

    The ALMA team is composed of: Z. Zhang (Institute for Astronomy, University of Edinburgh, Edinburgh, UK; European Southern Observatory, Garching bei München, Germany), D. Romano (INAF, Astrophysics and Space Science Observatory, Bologna, Italy), R. J. Ivison (European Southern Observatory, Garching bei München, Germany; Institute for Astronomy, University of Edinburgh, Edinburgh, UK), P .P. Papadopoulos (Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece; Research Center for Astronomy, Academy of Athens, Athens, Greece;) and F. Matteucci (Trieste University; INAF, Osservatorio Astronomico di Trieste; INFN, Sezione di Trieste, Trieste, Italy)

    The VLT team is composed of: F. R. N. Schneider ( Department of Physics, University of Oxford, UK), H. Sana (Institute of Astrophysics, KU Leuven, Belgium), C. J. Evans ( UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. M. Bestenlehner (Max-Planck-Institut für Astronomie, Heidelberg, Germany; Department of Physics and Astronomy, University of Sheffield, UK), N. Castro (Department of Astronomy, University of Michigan, USA), L. Fossati (Austrian Academy of Sciences, Space Research Institute, Graz, Austria), G. Gräfener (Argelander-Institut für Astronomie der Universität Bonn, Germany), N. Langer (Argelander-Institut für Astronomie der Universität Bonn, Germany), O. H. Ramírez-Agudelo (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), C. Sabín-Sanjulián (Departamento de Física y Astronomía, Universidad de La Serena, Chile), S. Simón-Díaz (Instituto de Astrofísica de Canarias, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain), F. Tramper (European Space Astronomy Centre, Madrid, Spain), P. A. Crowther (Department of Physics and Astronomy, University of Sheffield, UK), A. de Koter (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands; Institute of Astrophysics, KU Leuven, Belgium), S. E. de Mink (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands), P. L. Dufton (Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Northern Ireland, UK), M. Garcia (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), M. Gieles (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK), V. Hénault-Brunet (National Research Council, Herzberg Astronomy and Astrophysics, Canada; Department of Astrophysics/Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, Netherlands), A. Herrero (Departamento de Física y Astronomía, Universidad de La Serena, Chile), R. G. Izzard (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK; Institute of Astronomy, The Observatories, Cambridge, UK), V. Kalari (Departamento de Astronomía, Universidad de Chile, Santiago, Chile), D. J. Lennon (European Space Astronomy Centre, Madrid, Spain), J. Maíz Apellániz (Centro de Astrobiología, CSIC–INTA, European Space Astronomy Centre campus, Villanueva de la Cañada, Spain), N. Markova (Institute of Astronomy with National Astronomical Observatory, Bulgarian Academy of Sciences, Smolyan, Bulgaria), F. Najarro (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), Ph. Podsiadlowski (Department of Physics, University of Oxford, UK; Argelander-Institut für Astronomie der Universität Bonn, Germany), J. Puls (Ludwig-Maximilians-Universität München, Germany), W. D. Taylor (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. Th. van Loon (Lennard-Jones Laboratories, Keele University, Staffordshire, UK), J. S. Vink (Armagh Observatory, Northern Ireland, UK) and C. Norman (Johns Hopkins University, Baltimore, USA; Space Telescope Science Institute, Baltimore, USA)

    Links

    Zhang et al. research paper
    Schneider et al. research paper
    Photos of ALMA
    Photos of the VLT

    See the full ESO article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition


    five-ways-keep-your-child-safe-school-shootings

    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.

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  • richardmitnick 2:42 pm on May 16, 2018 Permalink | Reply
    Tags: ALMA, , , , , , , , The very distant galaxy MACS1149-JD1   

    From European Southern Observatory and ALMA Observatory: “ALMA and VLT Find Evidence for Stars Forming Just 250 Million Years After Big Bang” 

    ESO 50 Large

    From European Southern Observatory

    and

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

    From ALMA

    16 May 2018

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

    Nicolas Laporte
    University College London
    London, United Kingdom
    Tel: +44 7452 807 591
    Email: n.laporte@ucl.ac.uk

    Richard Ellis
    University College London
    London, United Kingdom
    Tel: +44 7885 403 334
    Email: richard.ellis@ucl.ac.uk

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

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

    1
    Astronomers have used observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and ESO’s Very Large Telescope (VLT) to determine that star formation in the very distant galaxy MACS1149-JD1 started at an unexpectedly early stage, only 250 million years after the Big Bang. This discovery also represents the most distant oxygen ever detected in the Universe and the most distant galaxy ever observed by ALMA or the VLT. The results will appear in the journal Nature on 17 May 2018.

    2
    This image shows the huge galaxy cluster MACS J1149.5+223, whose light took over 5 billion years to reach us. The huge mass of the cluster is bending the light from more distant objects. The light from these objects has been magnified and distorted due to gravitational lensing. The same effect is creating multiple images of the same distant objects.
    Credit: NASA, ESA, S. Rodney (John Hopkins University, USA) and the SN team; T. Treu (University of California Los Angeles, USA), P. Kelly (University of California Berkeley, USA) and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI)

    Frontier Fields

    Gravitational Lensing NASA/ESA

    NASA/ESA Hubble Telescope

    3
    This image shows the very distant galaxy MACS1149-JD1, seen as it was 13.3 billion years ago and observed with ALMA. Credit: ALMA (ESO/NAOJ/NRAO), Hashimoto et al.


    ESOcast 161 Light: Distant galaxy reveals very early star formation.


    Zooming in on the distant galaxy MACS1149, and beyond


    Computer simulation of star formation in MACS1149-JD1


    Zooming in on the distant galaxy MACS 1149-JD1

    An international team of astronomers used ALMA to observe a distant galaxy called MACS1149-JD1. They detected a very faint glow emitted by ionised oxygen in the galaxy. As this infrared light travelled across space, the expansion of the Universe stretched it to wavelengths more than ten times longer by the time it reached Earth and was detected by ALMA. The team inferred that the signal was emitted 13.3 billion years ago (or 500 million years after the Big Bang), making it the most distant oxygen ever detected by any telescope [1]. The presence of oxygen is a clear sign that there must have been even earlier generations of stars in this galaxy.

    “I was thrilled to see the signal of the distant oxygen in the ALMA data,” says Takuya Hashimoto, the lead author of the new paper and a researcher at both Osaka Sangyo University and the National Astronomical Observatory of Japan. “This detection pushes back the frontiers of the observable Universe.”

    3
    Microwave spectrum of oxygen ions in MACS1149-JD1 detected with ALMA. It was originally infrared light with a wavelength of 88 micrometers, and ALMA detected it as microwaves with an increased wavelength of 893 micrometers due to the expansion of the Universe. Credit: Hashimoto et al. – ALMA (ESO/NAOJ/NRAO)

    In addition to the glow from oxygen picked up by ALMA, a weaker signal of hydrogen emission was also detected by ESO’s Very Large Telescope (VLT). The distance to the galaxy determined from this observation is consistent with the distance from the oxygen observation. This makes MACS1149-JD1 the most distant galaxy with a precise distance measurement and the most distant galaxy ever observed with ALMA or the VLT.

    “This galaxy is seen at a time when the Universe was only 500 million years old and yet it already has a population of mature stars,” explains Nicolas Laporte, a researcher at University College London (UCL) in the UK and second author of the new paper. “We are therefore able to use this galaxy to probe into an earlier, completely uncharted period of cosmic history.”

    For a period after the Big Bang there was no oxygen in the Universe; it was created by the fusion processes of the first stars and then released when these stars died. The detection of oxygen in MACS1149-JD1 indicates that these earlier generations of stars had been already formed and expelled oxygen by just 500 million years after the beginning of the Universe.

    But when did this earlier star formation occur? To find out, the team reconstructed the earlier history of MACS1149-JD1 using infrared data taken with the NASA/ESA Hubble Space Telescope and the NASA Spitzer Space Telescope. They found that the observed brightness of the galaxy is well-explained by a model where the onset of star formation corresponds to only 250 million years after the Universe began [2].

    NASA/Spitzer Infrared Telescope

    The maturity of the stars seen in MACS1149-JD1 raises the question of when the very first galaxies emerged from total darkness, an epoch astronomers romantically term “cosmic dawn”. By establishing the age of MACS1149-JD1, the team has effectively demonstrated that galaxies existed earlier than those we can currently directly detect.

    Richard Ellis, senior astronomer at UCL and co-author of the paper, concludes: “Determining when cosmic dawn occurred is akin to the Holy Grail of cosmology and galaxy formation. With these new observations of MACS1149-JD1 we are getting closer to directly witnessing the birth of starlight! Since we are all made of processed stellar material, this is really finding our own origins.”
    ESO Notes

    [1] ALMA has set the record for detecting the most distant oxygen several times. In 2016, Akio Inoue at Osaka Sangyo University and his colleagues used ALMA to find a signal of oxygen emitted 13.1 billion years ago. Several months later, Nicolas Laporte of University College London used ALMA to detect oxygen 13.2 billion years ago. Now, the two teams combined their efforts and achieved this new record, which corresponds to a redshift of 9.1.

    [2] This corresponds to a redshift of about 15.

    More information

    ALMA Notes

    [1] The measured redshift of galaxy MACS1149-JD1 is z=9.11. A calculation based on the latest cosmological parameters measured with Planck (H0=67.3 km/s/Mpc, Ωm=0.315, Λ=0.685: Planck 2013 Results) yields the distance of 13.28 billion light-years. Please refer to “Expressing the distance to remote objects” for the details.

    [2] The galaxy GN-z11 is thought to be located 13.4 billion light-years away based on observations with the Hubble Space Telescope (HST). But the precision of the distance measurement with HST low-resolution spectroscopy is significantly lower than that of ALMA’s measurement using a single emission line from atoms.

    These results are published in a paper entitled: “The onset of star formation 250 million years after the Big Bang”, by T. Hashimoto et al., to appear in the journal Nature on 17 May 2018.

    The research team members are: Takuya Hashimoto (Osaka Sangyo University/National Astronomical Observatory of Japan, Japan), Nicolas Laporte (University College London, United Kingdom), Ken Mawatari (Osaka Sangyo University, Japan), Richard S. Ellis (University College London, United Kingdom), Akio. K. Inoue (Osaka Sangyo University, Japan), Erik Zackrisson (Uppsala University, Sweden), Guido Roberts-Borsani (University College London, United Kingdom), Wei Zheng (Johns Hopkins University, Baltimore, Maryland, United States), Yoichi Tamura (Nagoya University, Japan), Franz E. Bauer (Pontificia Universidad Católica de Chile, Santiago, Chile), Thomas Fletcher (University College London, United Kingdom), Yuichi Harikane (The University of Tokyo, Japan), Bunyo Hatsukade (The University of Tokyo, Japan), Natsuki H. Hayatsu (The University of Tokyo, Japan; ESO, Garching, Germany), Yuichi Matsuda (National Astronomical Observatory of Japan/SOKENDAI, Japan), Hiroshi Matsuo (National Astronomical Observatory of Japan/SOKENDAI, Japan, Sapporo, Japan), Takashi Okamoto (Hokkaido University, Sapporo, Japan), Masami Ouchi (The University of Tokyo, Japan), Roser Pelló (Université de Toulouse, France), Claes-Erik Rydberg (Universität Heidelberg, Germany), Ikkoh Shimizu (Osaka University, Japan), Yoshiaki Taniguchi (The Open University of Japan, Chiba, Japan), Hideki Umehata (The University of Tokyo, Japan) and Naoki Yoshida (The University of Tokyo, Japan).

    See the full ESO article here .

    See the full ALMA 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.

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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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    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT.

    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

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    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 2:59 pm on April 30, 2018 Permalink | Reply
    Tags: ALMA, , , , , , The laws of star formation challenged   

    From Centre National de la Recherche Scientifique (CNRS): “The laws of star formation challenged” 

    CNRS bloc

    Centre National de la Recherche Scientifique [The National Center for Scientific Research ]

    30 April 2018

    An international team led by researchers at CNRS, Université Grenoble Alpes and the French Alternative Energies and Atomic Energy Commission (CEA) has challenged currently held ideas about star formation. The unprecedented resolution of the observations obtained using the Atacama Large Millimetre/Submillimetre Array (ALMA) enabled them to measure the quantity of high-mass star-forming cores in a remote, very active region of our Galaxy, and show that there is a higher proportion of them there than expected.

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

    Published in Nature Astronomy, the findings could challenge the widespread assumption that the mass distribution of a population of star-forming cores is identical to that of the stars they spawn.

    n space, hidden behind the dusty veils of nebulae, clouds of gas clump together and collapse, forming the structures from which stars are born: star-forming cores. These cluster together, accumulate matter and fragment, eventually giving rise to a cluster of young stars of various masses, whose distribution was described by Edwin Salpeter as an astrophysical law in 1955.

    Astronomers had already noticed that the ratio of massive objects to non-massive objects was the same in clusters of star-forming cores as in clusters of newly-formed stars. This suggested that the mass distribution of stars at birth, known as the IMF1, was simply the result of the mass distribution of the cores from which they formed, known as the CMF2. However, this conclusion resulted from the study of the molecular clouds closest to our Solar System, which are not very dense and therefore not very representative of the diversity of such clouds in the Galaxy. Is the relationship between the CMF and the IMF universal? What do we observe when we look at denser, more distant clouds?

    These were the questions asked by researchers at the Grenoble Institute of Planetology and Astrophysics (CNRS/Université Grenoble Alpes) and the Astrophysics, Instrumentation and Modelling Laboratory, (CNRS/CEA/Université Paris Diderot)3 when they started to observe the active star-formation region W43-MM1, whose structure is far more typical of molecular clouds in our Galaxy than those observed previously. Thanks to the unprecedented sensitivity and spatial resolution of the ALMA antenna array in Chile, the researchers were able to establish a statistically robust core distribution over an unmatched range of masses, from solar-type stars to stars 100 times more massive. To their surprise, the distribution did not obey Salpeter’s 1955 law.

    It turned out that, in the W43-MM1 cloud, there was an overabundance of massive cores, while less massive cores were under-represented. These findings call into question not only the relationship between the CMF and the IMF, but even the supposedly universal nature of the IMF. The mass distribution of young stars may not be the same everywhere in our Galaxy, contrary to what is currently assumed. If this turns out to be the case, the scientific community will be forced to re-examine its calculations about star formation and, eventually, any estimates that depend on the number of massive stars, such as the chemical enrichment of the interstellar medium, the numbers of black holes and supernovae, etc.

    The teams will continue their work with ALMA within a consortium of around forty researchers. Their aim is to study 15 regions similar to W43-MM1 in order to compare their CMFs and ascertain whether the characteristics of this cloud can be generalised.

    2
    The active star-formation region W43-MM1, as observed using the world’s largest millimetre interferometer, ALMA. The high number of star formation sites, known as cores and here identified by ellipses, are evidence of the intense star formation activity in this region. © ESO/ALMA/F. Motte/T. Nony/F. Louvet/Nature Astronomy.

    See the full article here .

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    CNRS encourages collaboration between specialists from different disciplines in particular with the university thus opening up new fields of enquiry to meet social and economic needs. CNRS has developed interdisciplinary programs which bring together various CNRS departments as well as other research institutions and industry.

    Interdisciplinary research is undertaken in the following domains:

    Life and its social implications
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  • richardmitnick 4:01 pm on April 12, 2018 Permalink | Reply
    Tags: ALMA, ALMA Deepens Mystery about the relation between Supermassive Black Holes and their Host Galaxies, , , , , ,   

    From ALMA: “ALMA Deepens Mystery about the relation between Supermassive Black Holes and their Host Galaxies” 

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

    ALMA

    20 February, 2018 [This one got away from me.]

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

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

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

    Science paper
    No Sign of Strong Molecular Gas Outflow in an Infrared-bright Dust-obscured Galaxy with Strong Ionized-gas Outflow
    The Astrophysical Journal

    Using the Atacama Large Millimeter/submillimeter Array (ALMA) to observe an active galaxy with a strong ionized gas outflow from the galactic center, astronomers have obtained a result making astronomers even more puzzled: an unambiguous detection of carbon monoxide (CO) gas associated with the galactic disk. However, they have also found that the CO gas which settles in the galaxy is not affected by the strong ionized gas outflow launched from the galactic center.

    According to a popular scenario explaining the formation and evolution of galaxies and supermassive black holes, radiation from galactic centers, where supermassive black holes are, can significantly influence the molecular gas (such as CO) and the star formation activities of the galaxies.

    ALMA result shows that the ionized gas outflow driven by the supermassive black hole does not necessarily affect its host galaxy. This result “has made the co-evolution of galaxies and supermassive black holes more puzzling,” explains Dr. Yoshiki Toba from the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan), and main author of this research. “The next step is looking into more data of this kind of galaxies. That is crucial for understanding the full picture of the formation and evolution of galaxies and supermassive black holes”.

    Answering the question “How did galaxies form and evolve during the 13.8-billion-year history of the universe?” has been one top issue in modern astronomy. Studies already revealed that almost all massive galaxies harbor a supermassive black hole at their centers. In recent findings, studies further showed the tight correlation between the mass of black holes and those of their host galaxies. This correlation suggests that supermassive black holes and their host galaxies have evolved together and they closely interacted each other as they grew, as known as the co-evolution of galaxies and supermassive black holes.

    The gas outflow driven by a supermassive black hole at the galactic center recently has become the focus of attention as it possibly is playing a key role in the co-evolution of galaxies and black holes. A widely accepted idea has described this phenomenon as the intense radiation from the galactic center in which is the supermassive black hole ionizes [1] the surrounding gas, even affecting the molecular gas that is the ingredient of star formation. The strong radiation activates [2] or suppresses [3] the star formation of galaxies. However, “we astronomers do not understand the real relation between the activity of supermassive black holes and star formation in galaxies,” says Tohru Nagao, Professor at Ehime University. “Therefore, many astronomers including us are eager to observe the real scene of the interaction between the nuclear outflow and the star-forming activities, for revealing the mystery of the co-evolution.”

    2
    Figure 1: Image of a DOG, WISE1029. The left and right panels show an optical image from the Sloan Digital Sky Survey (SDSS), and mid-infrared image from WISE, respectively. The image size is 30 square arcsecond (1 arcsecond is 1/3600 degree). It is clear that DOGs are faint in the optical, but are incredibly bright in the infrared. The SDSS spectrum indicates that strong ionized gas is outflowing toward us from WISE1029. Credit: Sloan Digital Sky Survey/NASA/JPL-Caltech

    Astronomers believe that DOGs harbor actively growing supermassive black holes in their nuclei [4]. In particular, one DOG (WISE1029+0501, hereafter WISE1029) is outflowing gas ionized by the intense radiation from its supermassive black hole. WISE1029 is known as an extreme case concerning ionized gas outflow, and this particular factor has motivated the researchers to see what happens to its molecular gas.

    By making use of ALMA’s outstanding sensitivity which is excellent in investigating properties of molecular gas and star-forming activities in galaxies, the team conducted their research by observing the CO and the cold dust of galaxy WISE1029 (Figure 2). After detailed analysis, surprisingly they found, there is no sign of significant molecular gas outflow. Furthermore, star-forming activity is neither activated nor suppressed. This indicates that a strong ionized gas outflow launched from the supermassive black hole in WISE1029 neither significantly affect the surrounding molecular gas nor the star formation.

    3
    Figure 2: Emission from carbon monoxide (left) and cold dust (right) in WISE1029 observed by ALMA. The image size is 3 square arcsecond. Credit: ALMA (ESO/NAOJ/NRAO), Toba et al.

    There have been many reports saying that the ionized gas outflow driven by the accretion power of a supermassive black hole has an enormous impact on surrounding molecular gas (e.g., *2,3). However, it is a rare case that there is no close interaction between ionized and molecular gas as the researchers are reporting this time. Yoshiki and its team’s result suggests that the radiation from a supermassive black hole does not always affect the molecular gas and star formation of its host galaxy.

    3
    Figure 3: A schematic view of the fact that an ionized gas outflow (green) driven by the central supermassive black hole does not affect the star formation of its host galaxy. This situation may occur if the ionized gas is outflowing perpendicularly to the molecular gas. Credit: ALMA (ESO/NAOJ/NRAO)

    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.

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    Figure 3: A schematic view of the fact that an ionized gas outflow (green) driven by the central supermassive black hole does not affect the star formation of its host galaxy. This situation may occur if the ionized gas is outflowing perpendicularly to the molecular gas. Credit: ALMA (ESO/NAOJ/NRAO)

    While their result is making the co-evolution of galaxies and supermassive black holes more puzzling, Yoshiki and his team are exciting about revealing the full picture of the scenario. He says that “understanding such co-evolution is crucial for astronomy. By collecting statistical data of this kind of galaxies and continuing in more follow-up observations using ALMA, we hope to reveal the truth.”
    Notes

    [1] It is a phenomenon where ultraviolet and X-ray radiations make a neutral gas plasma state.

    [2] See the ALMA news Black-Hole-Powered Jets Forge Fuel for Star Formation</em> on February 15, 2017

    [3] See the ALMA news Chaotic Turbulence Roiling ‘Most Luminous Galaxy’ in the Universe on February 18, 2016.

    [4] See the press release from Subaru Telescope Discovering Dust-Obscured Active Galaxies as They Grow</em> on August 26, 2015.
    Additional Information

    These observation results were published as Toba et al. No sign of strong molecular gas outflow in an infrared-bright dust-obscured galaxy with strong ionized-gas outflow in the Astrophysical Journal [link is above.] in December 2017.

    This research was conducted by:

    Yoshiki Toba (Academia Sinica), Shinya Komugi (Kogakuin University), Tohru Nagao (Ehime University), Takuji Yamashita (Ehime University), Wei-Hao Wang (Academia Sinica), Masatoshi Imanishi (National Astronomical Observatory of Japan), Ai-Lei Sun (Academia Sinica, now Johns Hopkins University).

     
  • richardmitnick 12:32 pm on April 6, 2018 Permalink | Reply
    Tags: , ALMA, , , , , Magnetic Fields Versus Gravity,   

    From AAS NOVA: ” Magnetic Fields Versus Gravity” 

    AASNOVA

    AAS NOVA

    6 April 2018
    Kerry Hensley

    1
    Composite optical and infrared image of Milky Way star-forming region S106. Tracing the magnetic fields threaded through star-forming regions like this one can help us learn more about how stars form. [NASA/ESA/Hubble Heritage Team (STScI/AURA)/Subaru Telescope (NAOJ)]

    NASA/ESA Hubble Telescope


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

    Deep within giant molecular clouds, hidden by dense gas and dust, stars form. Unprecedented data from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the intricate magnetic structures woven throughout one of the most massive star-forming regions in the Milky Way.

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

    How Stars Are Born

    2
    The Horsehead Nebula’s dense column of gas and dust is opaque to visible light, but this infrared image reveals the young stars hidden in the dust. [NASA/ESA/Hubble Heritage Team]

    Simple theory dictates that when a dense clump of molecular gas becomes massive enough that its self-gravity overwhelms the thermal pressure of the cloud, the gas collapses and forms a star. In reality, however, star formation is more complicated than a simple give and take between gravity and pressure. The dusty molecular gas in stellar nurseries is permeated with magnetic fields, which are thought to impede the inward pull of gravity and slow the rate of star formation.

    How can we learn about the magnetic fields of distant objects? One way is by measuring dust polarization. An elongated dust grain will tend to align itself with its short axis parallel to the direction of the magnetic field. This systematic alignment of the dust grains along the magnetic field lines polarizes the dust grains’ emission perpendicular to the local magnetic field. This allows us to infer the direction of the magnetic field from the direction of polarization.

    Tracing Magnetic Fields

    3
    Magnetic field orientations for protostars e2 and e8 derived from Submillimeter Array observations (panels a through c) and ALMA observations (panels d and e). [Adapted from Koch et al. 2018]

    CfA Submillimeter Array Mauna Kea, Hawaii, USA,4,207 m (13,802 ft) above sea level

    Patrick Koch (Academia Sinica, Taiwan) and collaborators used high-sensitivity ALMA observations of dust polarization to learn more about the magnetic field morphology of Milky Way star-forming region W51. W51 is one of the largest star-forming regions in our galaxy, home to high-mass protostars e2, e8, and North.

    The ALMA observations reveal polarized emission toward all three sources. By extracting the magnetic field orientations from the polarization vectors, Koch and collaborators found that the molecular cloud contains an ordered magnetic field with never-before-seen structures. Several small clumps on the perimeter of the massive star-forming cores exhibit comet-shaped magnetic field structures, which could indicate that these smaller cores are being pulled toward the more massive cores.

    These findings hint that the magnetic field structure can tell us about the flow of material within star-forming regions — key to understanding the nature of star formation itself.

    Guiding Star Formation

    4
    Maps of sin ω for two of the protostars (e2 and e8) and their surroundings. [Adapted from Koch et al. 2018]

    Do the magnetic fields in W51 help or hinder star formation? To explore this question, Koch and collaborators introduced the quantity sin ω, where ω is the angle between the local gravity and the local magnetic field.

    When the angle between gravity and the magnetic field is small (sin ω ~ 0), the magnetic field has little effect on the collapse of the cloud. If gravity and the magnetic field are perpendicular (sin ω ~ 1), gravity can slow the infall of gas and inhibit star formation.

    Based on this parameter, Koch and collaborators identified narrow channels where gravity acts unimpeded by the magnetic field. These magnetic channels may funnel gas toward the dense cores and aid the star-formation process.

    The authors’ observations demonstrate just one example of the broad realm ALMA’s polarimetry capabilities have opened to discovery. These and future observations of dust polarization will continue to reveal more about the delicate magnetic structure within molecular clouds, further illuminating the role that magnetic fields play in star formation.

    Citation

    Patrick M. Koch et al 2018 ApJ 855 39. http://iopscience.iop.org/article/10.3847/1538-4357/aaa4c1/meta

    See the full article here .

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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 5:24 pm on April 2, 2018 Permalink | Reply
    Tags: ALMA, , , , , , , , Rings and Gaps in a Developing Planetary System   

    From CfA: “Rings and Gaps in a Developing Planetary System” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    1
    A model of the dust ring around the young star Elias 24, produced from simulations based on new ALMA millimeter images of the system. The model finds that the dust was shaped by a planet with 70% of Jupiter’s mass located about 60 au from the star. Dipierro et al. 2018

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

    The discovery of an exoplanet has most often resulted from the monitoring of a star’s flicker (the transiting method) or its wobble (the radial velocity method).

    Planet transit. NASA/Ames

    Radial Velociity Method. ESO

    Discovery by direct imaging is rare because it is so difficult to spot a faint exoplanet hidden in the glare of its host star. The advent of the new generation of radio interferometers (as well as improvements in near-infrared imaging), however, has enabled the imaging of protoplanetary discs and, in the disc substructures, the inference of orbiting exoplanets. Gaps and ring-like structures are particularly fascinating clues to the presence or ongoing formation of planets.

    Rings of dust have already been identified in many protoplanetary systems from their infrared and submillimeter emission. The origin of these rings is debated. They might have formed from dust “pile-up,” dust settling, gravitational instabilities, or even from variations in the optical properties of the dust. Alternatively, the rings could result dynamically from the orbital motions of planets that have already developed or that are well on their way. Planets will induce waves in the dusty discs which, as they dissipate, can produce gaps or rings. Key to solving the problem is recognizing that different sized dust grains behave differently, with small grains being strongly coupled to the gas and so track the gas mass, whereas larger grains (millimeter-sized or larger) tend to follow pressure gradients and concentrate near gap edges.

    CfA astronomers Sean Andrews and David Wilner were members of a team of scientists who used the ALMA facility to image the dust around the young star Elias 24 with a resolution of about 28 au (one astronomical unit being about the average distance of the Earth from the Sun). The astronomers find evidence for gaps and rings and, assuming these are produced by an orbiting planet, they model the system allowing both the planet’s mass and location and the dust’s density distribution to evolve. Their best model explains the observations quite well: after about forty-four thousand years the inferred planet has a mass 70% of Jupiter’s mass and is located 61.7 au from the star. The result reinforces the conclusion that both gaps and rings are prevalent in a wide variety of young circumstellar disks, and signal the presence of orbiting planets.

    Science paper:
    Rings and gaps in the disc around Elias 24 revealed by ALMA .
    MNRAS

    See the full article here .

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    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 1:38 pm on March 16, 2018 Permalink | Reply
    Tags: ALMA, ALMA - Breathless Science, , , , , , ,   

    From ESOblog: “Breathless Science” 

    ESO 50 Large

    ESOblog

    16 March 2018

    1
    On the Ground

    At a soaring altitude of 5100 metres above sea level, the ALMA Observatory is one of the world’s most extreme work environments. Athletes and hikers who climb this high usually move up slowly in altitude to adjust to the lower oxygen levels. But at ALMA, workers go from the Operations Support Facility (OSF) at 2900 metres up to the array of antennas at 5100 metres in less than an hour — and they go up and down daily. We spoke to Ivan Lopez, ALMA’s Safety Manager, to find out how to minimise the negative effects of high altitude on the health of workers.

    2
    Iván López

    Q: Tell us about your staff — what kinds of people work at ALMA and the OSF?

    A: We have on average 250 people at our observatory. From those, approximately 50 are exposed to intermittent hypoxia, which is a medical condition where the body does not get sufficient oxygen. We need all types of workers and their skills: from cleaning staff, to electrical and mechanical technicians, to a range of civil engineers, to our scientists. The astronomers who end up using ALMA data seldom need to work at the high site.

    Q: What are the conditions like for your staff?

    A: Our facilities in the Atacama Desert are essentially like small towns located in remote places, where the access to entertainment, leisure, medical care, and contact with loved ones is limited. This takes its toll on the sociological, psychological and personal development of our teams. But the environment is one of our biggest challenges. The ALMA site of is one of the driest on Earth, with very extreme weather and fast changes between conditions — we can have all four seasons in one day!

    Perhaps most importantly, we are confronted with rapid altitude changes that physiologically affect our workers’ bodies. Low oxygen levels make our work unsafe and more difficult. Since we must travel from 2900 to 5100 metres above sea level in just 45 minutes, we are exposed to hypoxia.

    3
    This panoramic view of the Chajnantor Plateau shows ALMA bathed in a spectacular sunset. It captures the feeling of solitude experienced at the ALMA site and the otherworldly appearance of the terrain.
    Credit: Y. Beletsky/ESO.

    Q: What is hypoxia and what effects does it have?

    A: Hypoxia is a deficiency in the amount of oxygen that reaches the body’s tissues. The severity of its effects depends on the length of exposure and the person’s physiology. We’ve been working with the University of Zurich in Switzerland, the University of Calgary in Canada, and the Universidad Católica del Norte in Chile to study the effects of hypoxia, as well as possible solutions for how to reduce these effects in our workers. It’s a great win-win for all of us. The medical researchers enjoy working with us — ALMA is like a natural laboratory for these studies due to its high altitude — and we, in turn, learn new information that we can use to take precautionary measures for our staff.

    4
    ALMA Transporter Operator Patricio Saavedra working with oxygen at 5000 metres. Credit: ESO/Max Alexander.

    In the latest round of studies in 2016, researchers examined our workers who volunteered over six weeks, examining their cognitive skills, sleep quality, breathing patterns, blood flow to the brain, and changes in blood flow between the heart and lungs. The studies are currently being reviewed and will be published this year. Among the many things we learned, we found out that hypoxia influences a worker’s quality of sleep, attention span, and short-term memory. This poses a real danger, as it negatively impacts the quality, productivity and safety of our workers and equipment, since many of our staff work on tasks that require a high level of concentration. This means that accident probability goes up since people are less alert.

    Q: Facing these risks, how do you ensure that staff working at ALMA and the OSF are safe?

    A: The results of these ongoing studies have made us change our daily programme, activities, and procedures to create a safer working environment. We’re currently making changes to our approach to safety and health, which has been used as a model across our facilities and Chile. We also carry out our High Altitude Medical Evaluation every year, which means that each worker gets a green light from a doctor more often than required by the Chilean authorities.

    _______________________________________________
    Among the many things we have changed, we have made the use of portable medical oxygen mandatory.
    _______________________________________________

    Among the many things we have changed, we have made the use of portable medical oxygen mandatory for all drivers from the 3000 metres above sea level and up, and for all workers on the Chajnantor Plateau where the antennas are located. The O2 tanks have evolved from big, bulky, heavy cylinders to smaller lightweight tanks made of carbon fibre. At the beginning, they are uncomfortable for the worker to use, but they get used to it — we’ve even designed backpacks to carry the O2 tank everywhere. Since we use liquified O2 that is very dry, we monitor our workers and provide nasal sprays to moisturise their airways.

    4
    The Array Operations Site (AOS) is the basecamp for the routine operations of the ALMA facility and the second highest building in the world. The AOS Technical Building houses the ALMA correlator — the highest-altitude supercomputer in the world. The air is so thin that the correlator’s fan system requires twice the usual airflow to keep it cool. Here Enrique Garcia, a correlator technician, examines the supercomputer system while breathing oxygen from a tank in his backpack. Credit: ESO/Max Alexander.

    The AOS (Array Operations Site) technical building on the Chajnantor plateau is also now permanently oxygenated (we have a liquid oxygen plant installed). It is also recommended that drivers going up and down our road have a copilot; that staff should work in teams of at least two; that supervisors should plan their work activities to follow exact procedures, with workers following bullet lists of small tasks; and that workers should limit the number of working hours at high altitude, optimising their shifts.

    We limit the time that all our workers, including contractors, spend at 5100 metres. Each of our staff work on a roster — eight days working at the site, and six days off work back at sea level. The day that they arrive, they are not allowed to go up to the high site. The second day of their shift, they are allowed to go up for just four hours; the third day for six hours; and from the fourth to the eighth day, a maximum of eight hours. No one is allowed to sleep at the high site.

    6
    This is no ordinary truck — it is an ALMA transporter, called Lore. At 20 metres long and 10 metres wide, this is one of a pair of custom-designed vehicles used to transport the 66 antennas that make up ALMA. Credit: Enrico Sacchetti/ESO.

    We have also increased our medical staff to have one registered nurse, stationed at the OSF, plus two paramedics on shift at all times. The paramedics go out on-site to perform field checks and constantly monitor the workers. A medical doctor visits twice a week to attend to all the needs of our workers. We also continuously train our staff in the latest developments on how to handle hypoxia and develop new strategies such a special diet and exercise program.

    Q: Why does a special diet need to be developed?

    A: High altitude can make it more difficult for the body to digest food. Ideally, our workers should have small snacks at different times of the day, such as dried fruits, almonds, nuts, fresh juice, power bars — mostly fast-release energy foods. We need to avoid heavy meals because they will take longer to digest at such heights. For example, right now we have removed soda beverages, broccoli, onions, cauliflower, turkey, beans and legumes from the meals. Managing our workers’ diets is actually one of the biggest challenges we have since the local workers are used to having big meals — something that has been rooted in their culture for generations.

    Q: Have any workers experienced severe altitude sickness, or has there been an altitude-related accident?

    A: Our programme has been very effective, so we have not had a serious or fatal incident related to hypoxia. But this does not mean that we have not had emergencies! We’ve had three serious emergencies where workers needed to be carried down to the nearby city of Calama. Around 15 visitors have also experienced minor hypoxia-related symptoms that needed attention.

    Luckily, our polyclinic staff have over 10 years of experience working at high altitudes and are regularly trained to deal with emergency situations. Our polyclinic is also equipped with three ambulances, two portable hyperbaric chambers, a cardiac arrest device, an emergency crash cart, and we have a contract with Telemedicina for the remote monitoring of heart illnesses. So we are very prepared to deal with emergencies.

    Q: What are the long-term effects of working at high altitude?

    A: The scientific literature has found that there are some long-term effects to hypoxia, mostly related to untreated issues or precautions have not been taken; but the studies performed so far have mostly been related to athletes or people who have suffered hypoxia-related accidents. There is very little available information on workers like ours in the long term. That is the reason why we are taking extreme care, continually monitoring our workers and partnering with universities to perform further studies.

    Q: Tell us about your role as Safety Manager.

    A: My office handles Safety, Health, Environment and Security at the ALMA Observatory, which includes managing the well-being of our people, the assessment of equipment, risk prevention, and our fire brigade team. We are also in charge of taking care of our environment by imposing regulations and resolutions based on environmental impact studies. We manage and develop ALMA’s health program and are also in charge of the management of the security contract.

    7
    Inside the Operations Support Facility (OSF), over 2000 metres below Chajnantor Plateau, ALMA test scientists go through the process of calibrating and testing the accuracy of an antenna. Credit: ESO/M. Alexander.

    Q: Can the extreme conditions affect the actual machinery of ALMA?

    A: Yes, and our engineers are constantly reviewing and adapting changes to cope with this. Antenna parts are being constantly modified and designed so we can meet with the requirement of our scientific clients, and many parts that were supposed to last a certain amount of years are actually lasting half of that time. The amount of time predicted for workers to carry out tasks has also been affected.

    Bear in mind that we are currently one of the few organisations in the world that has a wide array of equipment operating at these altitudes in such extreme conditions. Most information about how to function at these heights has not yet been shared by companies, mostly in the mining industry, who face similar challenges. So we are learning as we go. Our team has people with experience gained at the observatories in Hawaii and at APEX so we try to use their knowledge as a basis for many processes.

    Q: Has ESO shared its findings with the wider community?

    A: Yes, we have. There is not yet an international regulation for working at high altitude, so the data collected at ALMA is groundbreaking in the field and serves as a reference for ongoing medical studies. We are proud to say that the Chilean government has used our results to develop and change the current Chilean regulations on hypoxia, and we have participated in labour and health conferences to explain our approach to hypoxia. We are also an active part of the Lake Louise Hypoxia conference that is held every two years, where worldwide researchers show and explain their findings. One Peruvian company is using our health programme as a model for their own.

    Other observatories also face the same problems as they build their telescopes at high altitudes to escape the effects of atmospheric distortion. We have formed a group of safety managers from different observatories who meet periodically to share experiences and findings.

    See the full article here .

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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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    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 10:57 am on March 11, 2018 Permalink | Reply
    Tags: A young planet makes a scene, ALMA, , , , , , ,   

    From ALMA via Manu: “A young planet makes a scene” 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    26 February 2018

    CONTACTS
    Nicolas Lira
    Coordinator of Communications and Education
    Observatory ALMA, Santiago, Chile
    Phone: +56 2 2467 6519
    Mobile: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Richard Hook
    Press Officer, European Southern Observatory
    Garching , Germany
    Phone: +49 89 3200 6655
    Mobile: +49 151 1537 3591
    Email: rhook@eso.org

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

    ALMA

    1
    A protoplanetary disk image captured by ALMA, AS 209

    Located in the young star – forming region of Ophiuchus, 410 light years from the Sun, a fascinating protoplanetary disk, named AS 209 , it is taking shape slowly. This wonderful image was captured using the high – resolution telescope ALMA, and reveals a curious pattern of rings and furrows in the dust surrounding a young star.

    Protoplanetary disks are dense gas and dust planes rotationally surrounding newly formed stars; on them is the stuff that can give rise to planets, moons , and other smaller bodies in orbit. With less than a million years, this system is very young, but already forming two grooves are defined on the disc.

    The outer groove is deep, broad and largely free of dust, which leads astronomers to think that there is a planet about the mass of Saturn orbiting (and it is about 800 light minutes from the central star and more than three times the distance between Neptune and the Sun!). As the planet shapes its path, the dust accumulates on the outer edge of its orbit, creating rings increasingly defined on the disk. The innermost groove is thinner and may have been formed by a smaller planet, but astronomers have raised the intriguing possibility that the great planet orbiting at greater distances has created both ways.

    This planet Saturn type, inferred so far from its parent star, raises fascinating questions about planetary formation at the edges of protoplanetary disks in particularly short time scales.

    Science paper:
    ALMA continuum observations of the protoplanetary disk AS 209,
    Astronomy & Astrophysics

    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.

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  • richardmitnick 10:32 am on February 26, 2018 Permalink | Reply
    Tags: ALMA, , , , , , Powerful Flare from Star Proxima Centauri Detected with ALMA,   

    From ALMA: “Powerful Flare from Star Proxima Centauri Detected with ALMA” 

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

    ALMA

    26 February, 2018

    Meredith MacGregor
    Carnegie Institution for Science
    Phone: +1 202 478 88 46
    Email: mmacgregor@carnegiescience.edu

    Alycia Weinberger
    Carnegie Institution for Science
    Phone: +1 202 478 88 52
    Email: aweinberger@carnegiescience.edu

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

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

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

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

    1
    An artist’s impression of a flare from Proxima Centauri, modeled after the loops of glowing hot gas seen in the largest solar flares. An artist’s impression of the exoplanet Proxima b is shown in the foreground. Proxima b orbits its star 20 times closer than the Earth orbits the Sun. A flare 10 times larger than a major solar flare would blast Proxima b with 4,000 times more radiation than the Earth gets from our Sun’s flares. Credit: Roberto Molar Candanosa / Carnegie Institution for Science, NASA/SDO, NASA/JPL.

    Puts habitability of nearby system into question

    Using data from the Atacama Large Millimeter/submillimeter Array (ALMA), a team of astronomers discovered that a powerful stellar flare erupted from Proxima Centauri last March. This finding, published in The Astrophysical Journal Letters, raises questions about the habitability of our solar system’s nearest exoplanetary neighbor, Proxima b, which orbits Proxima Centauri.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    At its peak, the newly recognized flare was 10 times brighter than our sun’s largest flares, when observed at similar wavelengths. Stellar flares have not been well studied at the millimeter and submillimeter wavelengths detected by ALMA, especially around stars of Proxima Centauri’s type, called M dwarfs, which are the most common in our galaxy.

    “March 24, 2017, was no ordinary day for Proxima Cen,” said Meredith MacGregor, an astronomer at the Carnegie Institution for Science, Department of Terrestrial Magnetism in Washington, D.C., who led the research with fellow Carnegie astronomer Alycia Weinberger. Along with colleagues from the Harvard-Smithsonian Center for Astrophysics’ David Wilner and Adam Kowalski and Steven Cranmer of the University of Colorado Boulder—they discovered the enormous flare when they reanalyzed ALMA observations taken last year.

    The flare increased Proxima Centauri’s brightness by 1,000 times over 10 seconds. This was preceded by a smaller flare; taken together, the whole event lasted fewer than two minutes of the 10 hours that ALMA observed the star between January and March of last year.

    Stellar flares happen when a shift in the star’s magnetic field accelerates electrons to speeds approaching that of light. The accelerated electrons interact with the highly charged plasma that makes up most of the star, causing an eruption that produces emission across the entire electromagnetic spectrum.

    “It’s likely that Proxima b was blasted by high energy radiation during this flare,” MacGregor explained, adding that it was already known that Proxima Centauri experienced regular, although smaller, X-ray flares. “Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”

    An earlier paper that also used the same ALMA data interpreted its average brightness, which included the light output of both the star and the flare together, as being caused by multiple disks of dust encircling Proxima Centauri, not unlike our own solar system’s asteroid and Kuiper belts.

    But when MacGregor, Weinberger, and their team looked at the ALMA data as a function of observing time, instead of averaging it all together, they were able to see the transient explosion of radiation emitted from Proxima Centauri for what it truly was.

    “There is now no reason to think that there is a substantial amount of dust around Proxima Cen,” Weinberger said. “Nor is there any information yet that indicates the star has a rich planetary system like ours.”

    2
    The brightness of Proxima Centauri as observed by ALMA over the two minutes of the event on March 24, 2017. The massive stellar flare is shown in red, with the smaller earlier flare in orange, and the enhanced emission surrounding the flare that could mimic a disk in blue. At its peak, the flare increased Proxima Centauri’s brightness by 1,000 times. The shaded area represents uncertainty. Credit: Meredith MacGregor, Carnegie.

    Additional Information

    The research team was composed by Meredith A. MacGregor [1,2], Alycia J. Weinberger [1], David J. Wilner [3], Adam F. Kowalski [4,5], Steven R. Cranmer [4].

    [1] Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015, USA.

    [2] NSF Astronomy and Astrophysics Postdoctoral Fellow
.

    [3] Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
.

    [4] Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Ave, Boulder, CO 80305, USA

    [5] National Solar Observatory, University of Colorado Boulder, 3665 Discovery Drive, Boulder, CO 80303, USA.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition

    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.

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