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  • richardmitnick 11:24 am on February 3, 2016 Permalink | Reply
    Tags: ALMA, , , IRAM, ,   

    From ALMA: “The Frigid Flying Saucer” 

    ESO ALMA Array
    ALMA

    03 February 2016
    Stephane Guilloteau
    Laboratoire d’Astrophysique de Bordeaux
    Floirac, France
    Email: stephane.guilloteau@u-bordeaux.fr

    Emmanuel di Folco
    Laboratoire d’Astrophysique de Bordeaux
    Floirac, France
    Email: emmanuel.di-folco@u-bordeaux.fr

    Vincent Pietu
    IRAM
    Grenoble, France
    Email: pietu@iram.fr

    Valeria Foncea

    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 467 6258

    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Richard Hook
    Public Information Officer, ESO

    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
    Tel: +1 434 296 0314
    Cell: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Masaaki Hiramatsu

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

    Tel: +81 422 34 3630

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

    ALMA Flying Saucer protoplanetary disc around 2MASS J16281370-2431391.
    The Flying Saucer protoplanetary disc around 2MASS J16281370-2431391. This close-up infrared view of the Flying Saucer comes from the NASA/ESA Hubble Space Telescope. Credit: ESO/NASA/ESA

    NASA Hubble Telescope
    NASA/ESA Hubble

    Astronomers have used the ALMA and IRAM telescopes to make the first direct measurement of the temperature of the large dust grains in the outer parts of a planet-forming disc around a young star. By applying a novel technique to observations of an object nicknamed the Flying Saucer they find that the grains are much colder than expected: –266 degrees Celsius. This surprising result suggests that models of these discs may need to be revised.

    The international team, led by Stephane Guilloteau at the Laboratoire d’Astrophysique de Bordeaux, France, measured the temperature of large dust grains around the young star 2MASS J16281370-2431391 in the spectacular Rho Ophiuchi star formation region, about 400 light-years from Earth.

    The Rho Ophiuchi star formation region in the constellation of Ophiuchus.
    The Rho Ophiuchi star formation region in the constellation of Ophiuchus. This wide-field view shows a spectacular region of dark and bright clouds, forming part of a region of star formation in the constellation of Ophiuchus (The Serpent Bearer). This picture was created from images in the Digitized Sky Survey 2. Credit: ESO/Digitized Sky Survey 2

    This star is surrounded by a disc of gas and dust — such discs are called protoplanetary discs as they are the early stages in the creation of planetary systems. This particular disc is seen nearly edge-on, and its appearance in visible light pictures has led to its being nicknamed the Flying Saucer.

    The astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the glow coming from carbon monoxide molecules in the 2MASS J16281370-2431391 disc. They were able to create very sharp images and found something strange — in some cases they saw a negative signal! Normally a negative signal is physically impossible, but in this case there is an explanation, which leads to a surprising conclusion.

    Lead author Stephane Guilloteau takes up the story: “This disc is not observed against a black and empty night sky. Instead it’s seen in silhouette in front of the glow of the Rho Ophiuchi Nebula. This diffuse glow is too extended to be detected by ALMA, but the disc absorbs it. The resulting negative signal means that parts of the disc are colder than the background. The Earth is quite literally in the shadow of the Flying Saucer!”

    The team combined the ALMA measurements of the disc with observations of the background glow made with the IRAM 30-metre telescope in Spain [1].

    IRAM 30m Radio telescope
    IRAM 30-metre telescope

    They derived a disc dust grain temperature of only –266 degrees Celsius (only 7 degrees above absolute zero, or 7 Kelvin) at a distance of about 15 billion kilometers from the central star [2]. This is the first direct measurement of the temperature of large grains (with sizes of about one millimeter) in such objects.

    This temperature is much lower than the –258 to –253 degrees Celsius (15 to 20 Kelvin) that most current models predict. To resolve the discrepancy, the large dust grains must have different properties than those currently assumed, to allow them to cool down to such low temperatures.

    “To work out the impact of this discovery on disc structure, we have to find what plausible dust properties can result in such low temperatures. We have a few ideas — for example the temperature may depend on grain size, with the bigger grains cooler than the smaller ones. But it is too early to be sure,” adds co-author Emmanuel di Folco (Laboratoire d’Astrophysique de Bordeaux).

    If these low dust temperatures are found to be a normal feature of protoplanetary discs this may have many consequences for understanding how they form and evolve.

    For example, different dust properties will affect what happens when these particles collide, and thus their role in providing the seeds for planet formation. Whether the required change in dust properties is significant or not in this respect cannot yet be assessed.

    Low dust temperatures can also have a major impact for the smaller dusty discs that are known to exist. If these discs are composed of mostly larger, but cooler, grains than is currently supposed, this would mean that these compact discs can be arbitrarily massive, so could still form giant planets comparatively close to the central star.

    Further observations are needed, but it seems that the cooler dust found by ALMA may have significant consequences for the understanding of protoplanetary discs.

    Notes

    [1] The IRAM measurements were needed as ALMA itself was not sensitive to the extended signal from the background.

    [2] This corresponds to one hundred times the distance from the Earth to the Sun. This region is now occupied by the Kuiper Belt within the Solar System.

    Kuiper Belt
    Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.)

    Additional information

    This research was presented in a paper entitled The shadow of the Flying Saucer: A very low temperature for large dust grains, by S. Guilloteau et al., published in Astronomy & Astrophysics Letters.

    The team is composed of S. Guilloteau (University of Bordeaux/CNRS, Floirac, France), V. Piétu (IRAM, Saint Martin d’Hères, France), E. Chapillon (University of Bordeaux/CNRS; IRAM), E. Di Folco (University of Bordeaux/CNRS), A. Dutrey (University of Bordeaux/CNRS), T.Henning (Max Planck Institute für Astronomie, Heidelberg, Germany [MPIA]), D.Semenov (MPIA), T.Birnstiel (MPIA) and N. Grosso (Observatoire Astronomique de Strasbourg, Strasbourg, France).

    See the full article here .

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

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

    NRAO Small

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    NAOJ

     
  • richardmitnick 11:45 am on January 27, 2016 Permalink | Reply
    Tags: ALMA, , , , ,   

    From ALMA: “ALMA confirms predictions on the interaction between protoplanetary disks and planets” 

    ESO ALMA Array
    ALMA

    27 January 2016
    Héctor Cánovas
    Universidad de Valparaíso Valparaíso, Chile
    Tel: +56 032 – 299 5555
    Tel: +56 02 84144232
    E-mail: hector.canovas@uv.cl

    Valeria Foncea

    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 467 6258

    Cell: +56 9 75871963
    E-mail: vfoncea@alma.cl

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

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

    Cell: +49 151 1537 3591
    E-mail: rhook@eso.org

    Masaaki Hiramatsu

    Education and Public Outreach Officer, NAOJ Chile
    Observatory

    Tokyo, Japan

    Tel: +81 422 34 3630

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

    Protoplanetary disc from ALMA
    Image taken by ALMA of the dust ring that surrounds the young star Sz 91. This ring is primarily made up of mm-sized dust particles. The interaction between several recently formed planets and the protoplanetary disk that still surrounds the star probably generate the dust ring observed by ALMA.

    New observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) of the disk that surrounds a young star, less massive than the Sun, confirm theories about the interaction between recently formed planets and disks. A team of astronomers led by Héctor Cánovas from Universidad de Valparaíso and the Millennium ALMA Disk Nucleus (MAD) observed the dust ring possibly sculpted by planets in formation around the star Sz 91, at a distance roughly 650 light years from Earth.

    The results obtained show the first disk around a star that is less massive than ours – it has only half of the mass of our Sun – which simultaneously presents a migration of dust particles from the outermost zones and evident signs of interaction between young planets with the disk in the innermost zone.

    Planets are born in dust and gas disks that surround young stars and feed them with matter, leaving a “footprint” of this interaction in the structure of the disk. The theoretical models that study this interaction predict that the planets carve the protoplanetary disk, creating a “hole” in the innermost part of the disk, and preventing mm-sized dust particles (like grains of sand on a beach) from continuing their journey towards the central star. At the same time, dust particles in the outermost parts of the disk (the farthest from the star) are attracted by the gravitational force of the star.

    The combination of both effects should create dust structures in the form of a ring in disks that host recently formed giant planets on the inside.

    “The sharp image from ALMA shows a ring around the young star. And it is a surprisingly large ring, over three times the size of Neptune’s orbit (a radius of approximately 110 astronomical units (AU)” explains Héctor Cánovas.

    The image from ALMA only shows the ring, as the radio telescope detects the cold dust particles that make it up, and not the planets and the star, as these are primarily made up of hot gas.

    “Based on the current paradigm of planet-disk interactions, only giant planets orbiting the innermost parts of the disk can explain the presence of a ring with such a large radius,” indicates Antonio Hales, ALMA astronomer and member of the research team.

    The accumulation of dust particles in a narrow annular structure, as is the case with Sz91, can favor the formation of more planets, because the high density of dust particles in the ring would provide the ideal conditions for the dust particles to agglutinate and grow in size until they form small planetary nuclei.

    “The results of this investigation show that Sz91 is a highly important protoplanetary disk for the study of planetary formation, planet-disk interactions, and the evolution of these disks around stars of lower mass, as Sz91 shows evidence of all these processes simultaneously,” concludes Matthias Schreiber, coauthor of the study.

    Additional information

    This investigation was presented in an article entitled A ring-like concentration of mm-sized particles in Sz 91, written by Héctor Cánovas and collaborators, which will soon be published in the specialized journal Monthly Notices of the Royal Astronomical Society (MNRAS).

    The research team is made up of Héctor Cánovas, Claudio Cáceres, Matthias Schreiber, Adam Hardy (all from Universidad de Valparaíso and from the Millennium ALMA Disk Nucleus (MAD), Chile), Lucas Cieza (Universidad Diego Portales and MAD, Chile), Francois Ménard (Universidad de Chile) and Antonio Hales (JAO-ALMA, Chile).

    Link

    A ring-like concentration of mm-sized particles in Sz 91

    See the full article here .

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

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

    NRAO Small

    ESO 50

    NAOJ

     
  • richardmitnick 10:34 am on January 15, 2016 Permalink | Reply
    Tags: ALMA, , , Chaotic Turbulence Roiling 'Most Luminous Galaxy' in the Universe,   

    From ALMA: “Chaotic Turbulence Roiling ‘Most Luminous Galaxy’ in the Universe” 

    ESO ALMA Array
    ALMA

    15 January 2016
    Tanio Díaz Santos
    Núcleo de Astronomía, Facultad de Ingeniería
    Universidad Diego Portales, Santiago, Chile
    Tel: +56 2 2213 0480
    Email: tanio.diaz@mail.udp.cl

    Valeria Foncea

    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 467 6258

    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

    Masaaki Hiramatsu

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

    Tel: +81 422 34 3630

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

    Temp 1
    Artist impression of W2246-0526, a single galaxy glowing in infrared light as intensely as approximately 350 trillion suns. It is so violently turbulent that it may eventually jettison its entire supply of star-forming gas, according to new observations with ALMA. Credit: NRAO/AUI/NSF; Dana Berry / SkyWorks; ALMA (ESO/NAOJ/NRAO).

    The most luminous galaxy in the Universe –a so-called obscured quasar 12.4 billion light-years away – is so violently turbulent that it may eventually jettison its entire supply of star-forming gas, according to new observations with the Atacama Large Millimeter/submillimeter Array (ALMA).

    A team of researchers used ALMA to trace, for the first time, the actual motion of the galaxy’s interstellar medium – the gas and dust between the stars. What they found, according to Tanio Díaz-Santos of the Universidad Diego Portales in Santiago, Chile, and lead author of this study, is a galaxy “so chaotic that it is ripping itself apart.”

    Previous studies with NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft reveal that the galaxy, dubbed W2246-0526, is glowing in infrared light as intensely as approximately 350 trillion suns.

    NASA Wise Telescope
    NASA/WISE

    Evidence strongly suggests that this galaxy is actually an obscured quasar, a very distant galaxy [whi h] contains a voraciously feeding supermassive black hole at its center that is completely obscured behind a thick blanket of dust.

    This galaxy’s startling brightness is powered by a tiny, yet incredibly energetic disk of gas that is being superheated as it spirals in on the supermassive black hole. The light from this blazingly bright accretion disk is then absorbed by the surrounding dust, which re-emits the energy as infrared light.

    “These properties make this object a beast in the infrared,” said Roberto Assef, an astronomer with the Universidad Diego Portales and leader of the ALMA observing team. “The powerful infrared energy emitted by the dust then has a direct and violent impact on the entire galaxy, producing extreme turbulence throughout the interstellar medium.”

    The astronomers compare this turbulent action to a pot of boiling water. If these conditions continue, they say, the galaxy’s intense infrared radiation would boil away all of its interstellar gas.

    This galaxy belongs to a very unusual type of quasar known as Hot, Dust-Obscured Galaxies or Hot DOGs These objects are very rare; only 1 out of every 3,000 quasars observed by WISE belong to this class.

    The research team used ALMA to precisely map the motion of ionized carbon atoms throughout the entire galaxy. These atoms, which are tracers for interstellar gas, naturally emit infrared light, which becomes shifted to millimeter wavelengths as it travels the vast cosmic distances to Earth due to the expansion of the Universe.

    “Large amounts of ionized carbon were found in an extremely turbulent dynamic state throughout the galaxy,” Díaz-Santos describes. The data reveal that this interstellar material is careening anywhere from 500 to 600 kilometers per second across the entire galaxy.

    The astronomers believe that this turbulence is primarily due to the fact that the region around the black hole is at least 100 times more luminous than the rest of the host galaxy combined; in other quasars, the proportion is much more modest. This intense yet localized radiation exerts tremendous pressure on the entire galaxy, to potentially devastating effect.

    “We suspected that this galaxy was in a transformative stage of its life because of the enormous amount of infrared energy discovered with WISE,” said Peter Eisenhardt with NASA’s Jet Propulsion Laboratory in Pasadena, California, and scientific leader of the WISE mission. “Now ALMA has shown us that the raging furnace in this galaxy is making the pot boil over.”

    Current models of galactic dynamics combined with the ALMA data indicate that this galaxy is unstable and its interstellar gas is being blown away in all directions. This means that the galaxy’s Hot DOG days are numbered as it matures into a more traditional unobscured quasar.

    “If this pattern continues, it is possible that in the future W2246 ends up shedding a large part of the gas and dust it contains,” concludes Manuel Aravena also from the Universidad Diego Portales, and co-author of the study. “Only ALMA, with its unparalleled resolution, can allow us to see this object in high definition and fathom such an important episode in the life of this galaxy.”

    This article, The Strikingly Uniform, Highly Turbulent Interstellar Medium of The Most Luminous Galaxy in the Universe, will be published in the Astrophysical Journal Letters.

    From ESO article:

    This research was presented in a paper “The Strikingly Uniform, Highly Turbulent Interstellar Medium of The Most Luminous Galaxy in the Universe”, by T. Díaz-Santos et al., and will be published in the journal Astrophysical Journal Letters.

    The team is composed of T. Díaz-Santos (Universidad Diego Portales, Santiago, Chile), R. J. Assef (Universidad Diego Portales, Santiago, Chile), A. W. Blain (University of Leicester, UK) , C.-W. Tsai (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA) , M. Aravena (Universidad Diego Portales, Santiago, Chile), P. Eisenhardt (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA), J. Wu (University of California Los Angeles, California, USA), D. Stern (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA) and C. Bridge (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 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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    ESO 50

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  • richardmitnick 12:51 pm on December 18, 2015 Permalink | Reply
    Tags: ALMA, ALMA Trilateral Agreement, , , ,   

    From ALMA: “ALMA Trilateral Agreement Signing Ceremony” 

    ESO ALMA Array
    ALMA

    18 December 2015
    Nicolás Lira T.
    Education and Public Outreach Coordinator
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 24 67 65 19
    Cell: +56 9 94 45 77 26
    Email: nlira@alma.cl

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

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

    1
    The ALMA Trilateral Agreement was signed by Tim de Zeeuw, the Director General of ESO, Katsuhiko Sato, the President of NINS, and F. Fleming Crim, the Assistant Director of NSF on behalf of France A. Córdova, the Director of NSF. Credit: ALMA (ESO/NAOJ/NRAO)

    On December 15, 2015, the National Institutes of Natural Sciences of Japan (NINS), the European Southern Observatory (ESO), and the National Science Foundation (NSF) signed an agreement concerning the operations of ALMA. The new agreement signed in Tokyo provides the framework for the long-lasting operations of ALMA over the next 20 years.

    “As NINS, we have responsibility to fulfill our commitment to the operations of ALMA as a party of this agreement.”, told Katsuhiko Sato, the president of NINS, in his speech in the signing ceremony. “We hope our contributions could lead to significant scientific results with ALMA. And, our contributions will be beneficial to global advances in understanding the physics of the Universe as stated in the agreement.”

    The first resolution for ALMA was concluded at the ALMA Coordination Committee meeting held in Tokyo in 2001. This was the formal start of the Atacama Large Millimeter Array as an international collaboration project between Japan, US, and Europe. The ALMA construction budgets were approved in US and Europe in 2001 and 2002 respectively. While the budget in Japan was yet to be approved at that time, NSF and ESO signed a bilateral agreement in 2003 and started construction of ALMA. Japan finally secured the budget in 2004 and joined the project by signing an agreement for the construction of the enhanced ALMA. Japan brought an enhanced capability of submillimeter observations and “Atacama Large Millimeter/submillimeter Array” was realized.

    “Big telescopes demand big partnerships,” said Dr. Córdova, the director of NSF in her video message for the ceremony. “Today’s new trilateral agreement is evidence of that commitment. We mark a point when ALMA’s future is made brighter because of our three organizations’ zeal to learn more about the Universe where we all live.”

    “The ALMA conference which took place in Tokyo last year demonstrated that the dream of a truly transformational facility for astronomy has become a reality,” told Tim de Zeeuw, the Director General of ESO. “I am certain that the power and efficiency of the facility will continue to increase in the years to come. It is a testimony to the visionary and motivated individuals who laid the groundwork more than three decades ago, and turned it onto a reality.”.

    The construction and development of ALMA and initial observations have been carried out based on the agreement signed in 2004. With an inauguration ceremony held in 2013, ALMA formally became a fully-fledged observatory. A new agreement focusing on science operations have been prepared since then, and signed this time by Sato, de Zeeuw and F. Fleming Crim, the assistant director of NSF on behalf of France A. Córdova.

    The new agreement signals the continuing trust and cooperation between ESO, NSF and NINS as ALMA makes the transition from construction into full science operations that are expected to last over three decades.

    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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  • richardmitnick 12:18 pm on December 16, 2015 Permalink | Reply
    Tags: ALMA, , , Dust traps, ,   

    From ALMA: “‘Dust Trap’ around Distant Star May Solve Planet Formation Mystery” 2013 but Worthwhile 

    ESO ALMA Array
    ALMA

    06 June 2013 [Just re-advanced by ALMA in a different article]

    Valeria Foncea

    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 2467 6258

    Cell: +56 9 7587 1963
    E-mail: vfoncea@alma.cl

    Nienke van der Marel
    Leiden Observatory
    Leiden, The Netherlands
    Tel: +31 71 527 8472
    Cell: +31 62 268 4136
    Email: nmarel@strw.leidenuniv.nl

    Ewine van Dishoeck
    Leiden Observatory
    Leiden, The Netherlands
    Tel: +31 71 527 5814
    Email: ewine@strw.leidenuniv.nl

    Richard Hook
    Public Information Officer, ESO
    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

    Masaaki Hiramatsu

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

    Tel: +81 422 34 3630

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

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    1
    This artist’s impression shows the dust trap in the system Oph-IRS 48. The dust trap provides a safe haven for the tiny rocks in the disc, allowing them to clump together and grow to sizes that allow them to survive on their own. Credit: ESO/L. Calçada

    Temp 1
    Annotated image from the Atacama Large Millimeter/submillimeter Array (ALMA) showing the dust trap in the disc that surrounds the system Oph-IRS 48. The dust trap provides a safe haven for the tiny dust particles in the disc, allowing them to clump together and grow to sizes that allow them to survive on their own. The green area is the dust trap, where the bigger particles accumulate. The size of the orbit of Neptune is shown in the upper left corner to show the scale. Credit: ALMA (ESO/NAOJ/NRAO), Nienke van der Marel

    Astronomers using the new Atacama Large Millimeter/submillimeter Array (ALMA) have imaged a region around a young star where dust particles can grow by clumping together. This is the first time that such a “dust trap” has been clearly observed and modelled. It solves a long-standing mystery how dust particles in discs grow to larger sizes so that they can eventually form comets, planets, and other rocky bodies. The results are published in the journal Science on 7 June 2013.

    Astronomers now know that planets around other stars are plentiful. But they do not fully understand how they form and there are many aspects of planet (and comet and asteroid) formation that remain a mystery. However, new observations exploiting the power of ALMA are now answering one of the biggest questions: how do tiny grains of dust in the disc around a young star grow bigger and bigger — to eventually become rubble, and even boulders well beyond a meter in size?

    Computer models suggest that dust grains grow when they collide and stick together. However, when these bigger grains collide again at high speed they are often smashed to pieces and sent back to square one. Even when this does not happen, the models show that the larger grains would quickly move inwards because of friction between dust and gas and fall onto their parent star before they have a chance to grow even further.

    Somehow the dust needs a safe haven where the particles can continue growing until they are big enough to survive on their own [1]. To get past this vexing size limit, astronomers have theorized that swirling eddies in the disk could create dust traps, regions that enable dust particles to cling together, eventually setting the stage for the formation of larger and larger objects. But there was no observational proof of their existence up to now.

    Nienke van der Marel, a PhD student at Leiden Observatory in the Netherlands, and lead author of the article was using ALMA along with her co-workers, to study a disc called Oph-IRS 48 [2].

    They found that this system was circled by a ring of gas with a central hole that was probably created by an unseen planet or companion star. Earlier observations using ESO’s Very Large Telescope had already shown that the small dust particles also form a similar ring structure.

    ESO VLT Interferometer
    ESO/VLT

    But the new ALMA view of where the larger dust particles were found was very different!

    “At first the shape of the dust in the image was a complete surprise for us,” says van der Marel. “Instead of the ring we had expected to see, we found a very clear cashew-nut shape! We had to convince ourselves that this feature was real, but the strong signal and sharpness of the ALMA observations left no doubt about the structure. Suddenly we realized what we had found.”

    What had been discovered was a region where bigger dust grains were trapped and could grow much larger by colliding and sticking together. This was a dust trap — just what the theorists were looking for.

    As van der Marel explains: “It’s likely that we are looking at a kind of comet factory because the particles can grow in this dust trap up to cometary sizes of a few kilometers. The dust is not likely to form full-sized planets at this distance from the star. But in the near future ALMA will be able to observe dust traps closer to their parent stars, where the same mechanisms are at work. Such dust traps really would be the cradles for new-born planets.”

    The dust trap forms as bigger dust particles move in the direction of higher pressure. Computer modelling has shown that such a high pressure region can originate from the motions of the gas at the edge of a gas hole — just like the one found in this disc.

    “The combination of modelling work and high quality observations of ALMA makes this a unique project”, says Cornelis Dullemond from the Institute for Theoretical Astrophysics in Heidelberg, Germany, who is an expert on dust evolution and disc modeling and member of the team. “Around the time that these observations were obtained, we were working on models predicting exactly these kinds of structures: a very lucky coincidence.”

    The observations were made while the ALMA array was still being constructed. They made use of the ALMA Band 9 receivers [3] — European-made devices that allow ALMA to create its sharpest images.

    “These observations show that ALMA is capable of delivering transformational science, even with less than half of the full array in use,” says Ewine van Dishoeck of the Leiden Observatory, who has been a major driver of the ALMA project for more than 20 years. “The incredible jump in both sensitivity and image sharpness in Band 9 gives us the opportunity to study basic aspects of planet formation in ways that were simply not possible before.”

    Notes

    [1] The cause of the dust trap, in this case a vortex in the disc’s gas’, has typical life spans of hundreds of thousand of years. Even when the dust trap ceases to work, the dust accumulated in the trap would take millions of years to disperse providing ample time for the dust grains to grow larger. [back]

    [2] The name is a combination of the constellation name of the star-forming region where the system is found and the type of source, so Oph stands for the constellation of Ophiuchus (The Serpent Bearer), and the IRS stands for infrared source. The distance from Earth to Oph-IRS 48 is about 400 light-years. [back]

    [3] ALMA can observe in different frequency bands. Band 9, operating at wavelengths of about 0.4–0.5 millimeters, is the mode that so far provides the sharpest images .[back]

    More Information

    This research was presented in a paper A major asymmetric dust trap in a transition disk“, by van der Marel et al, to appear in the journal Science on 7 June 2013.

    The team is composed of Nienke van der Marel (Leiden Observatory, Leiden, the Netherlands), Ewine F. van Dishoeck (Leiden Observatory; Max-Planck-Institut für Extraterrestrische Physik Garching, Germany [MPE]), Simon Bruderer (MPE), Til Birnstiel (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA [CfA]), Paola Pinilla (Heidelberg University, Heidelberg, Germany), Cornelis P. Dullemond (Heidelberg University), Tim A. van Kempen (Leiden Observatory; Joint ALMA Offices, Santiago, Chile), Markus Schmalzl (Leiden Observatory), Joanna M. Brown (CfA), Gregory J. Herczeg (Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, China), Geoffrey S. Mathews (Leiden Observatory) and Vincent Geers (Dublin Institute for Advanced Studies, Dublin, Ireland).

    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 11:57 am on December 16, 2015 Permalink | Reply
    Tags: ALMA, , , ,   

    From ALMA: “ALMA Reveals Planetary Construction Sites” 

    ESO ALMA Array
    ALMA

    16 December 2015
    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    Richard Hook
    Public Information Officer, ESO
    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
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

    1
    Schematic view of a transitional disc around a young star
    This schematic diagram shows how the dust (brown) and gas (blue) is distributed around the star, and how a young planet is clearing the central gap. Credit: ALMA (ESO/NAOJ/NRAO)/M. Kornmesser

    2
    ALMA imaging of the transitional disc HD 135344B. This ALMA image combines a view of the dust around the young star HD 135344B (orange) with a view of the gaseous material (blue). The smaller hole in the inner gas is a telltale sign of the presence of a young planet clearing the disc. Credit ALMA (ESO/NOAJ/NRAO)

    3
    ALMA imaging of the transitional disc DoAr 44. This ALMA image combines a view of the dust around the young star DoAr 44 (orange) with a view of the gaseous material (blue). The smaller hole in the inner gas is a telltale sign of the presence of a young planet clearing the disc. Credit ALMA (ESO/NOAJ/NRAO)


    download mp4 video here.
    Animated artist’s impression of a transitional disc around a young star.
    Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found telltale differences between the gaps in the gas and the dust in discs around four young stars. These new observations are the clearest indications yet that planets with masses several times that of Jupiter have recently formed in these discs. Credit: ALMA (ESO/NAOJ/NRAO)/M. Kornmesser


    download mp4 video here.
    Animated schematic view of a transitional disc around a young star
    This schematic diagram shows how the dust (brown) and gas (blue) is distributed around the star, and how a young planet is clearing the central gap. Credit: ALMA (ESO/NAOJ/NRAO)/M. Kornmesser

    Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found telltale differences between the gaps in the gas and the dust in discs around four young stars. These new observations are the clearest indications yet that planets with masses several times that of Jupiter have recently formed in these discs. Measurements of the gas around the stars also provide additional clues about the properties of those planets.

    Planets are found around nearly every star, but astronomers still do not fully understand how — and under what conditions — they form. To answer such questions, they study the rotating discs of gas and dust present around young stars from which planets are built. But these discs are small and far from Earth, and the power of ALMA was needed for them to reveal their secrets.

    A special class of discs, called transitional discs, has a surprising absence of dust in their centers, in the region around the star. Two main ideas have been put forward to explain these mysterious gaps. Firstly, the strong stellar winds and intense radiation could have blown away or destroyed the encircling gas and dust [1]. Alternatively, massive young planets in the process of formation could have cleared the material as they orbit the star [2].

    The unparalleled sensitivity and image sharpness of ALMA have now allowed the team of astronomers, led by Nienke van der Marel from the Leiden Observatory in the Netherlands to map the distribution of gas and dust in four of these transitional discs better than ever before [3]. This in turn has allowed them to choose between the two options — photoevaporation or young planets — as the cause of the gaps for the first time.

    The new images show that there are significant amounts of gas within the dust gap [4]. But to the team’s surprise, this disc of gas also possessed a gap, up to three times smaller than that of the dust. This could only be explained by the scenario in which the newly formed massive planet cleared the gas as it travelled around their orbit, but trapped the dust particles further out [5].

    “Previous observations already hinted at the presence of gas inside the dust gaps,” explains Nienke van der Marel. “But as ALMA can image the material in the entire disc in much greater detail than other facilities, we could rule out the alternative photoevaporation scenario. The deep gap points clearly to the presence of planets with several times the mass of Jupiter, creating these caverns as they sweep through the disc.”

    Remarkably, these observations were conducted utilising just one tenth of the current resolving power of ALMA, as they were performed whilst half of the array was still under construction on the Chajnantor Plateau in northern Chile. Further studies are now needed to determine whether more transitional discs also point towards this planet-clearing scenario, although ALMA’s observations have, in the meantime, provided astronomers with a valuable new insight into the complex process of planetary formation.

    “All the transitional discs studied so far that have large dust cavities also have gas cavities. So, with ALMA, we can now find out where and when giant planets are being born in these discs, and compare these results with planet formation models,” says Ewine van Dishoeck, also of Leiden University and the Max Planck Institute for Extraterrestrial Physics in Garching [6]. “Direct planetary detection is just within reach of current instruments, and the next generation telescopes currently under construction, such as the European Extremely Large Telescope, will be able to go much further. ALMA is pointing out where they will need to look.”

    Notes

    [1] This process, which clears the dust and gas from the inside out, is known as photoevaporation.

    [2] Such planets are difficult to observe directly and previous studies at millimeter wavelengths have failed to achieve a sharp view of their inner, planet-forming zones where these different explanations could be put to the test. Other studies could not measure the bulk of the gas in these discs.

    [3] The four targets of these investigations were SR 21, HD 135344B (also known as SAO 206462), DoAr 44 and Oph IRS 48.

    [4] The gas present in transitional discs consists primarily of hydrogen, and is traced through observations of the carbon monoxide — or CO — molecule.

    [5] The process of dust trapping is explained in an earlier release.

    [6] Other examples include the HD 142527 (eso1301 and here) and J1604-2130 transitional discs.

    Additional information

    This research was presented in a paper entitled Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA, by N. van der Marel, et al., to appear in Astronomy & Astrophysics in December 2015.

    The team is composed of N. van der Marel (Leiden University, Leiden, the Netherlands; Institute for Astronomy, University of Hawaii, Honolulu, USA), E. F. van Dishoeck (Leiden University, Leiden, the Netherlands; Max Planck Institute for Extraterrestrial Physics in Garching, Germany), S. Bruderer (Max-Planck Institute for Extraterrestrial Physics, Garching, Germany), S. M. Andrews (Harvard-Smithsonian Center for Astrophysics, Massachusetts, USA), K. M. Pontoppidan (Space Telescope Science Institute, Baltimore, Maryland, USA), G. J. Herczeg (Peking University, Beijing, China), T. van Kempen (Leiden University, Leiden, the Netherlands) and A. Miotello (Leiden University, Leiden, the Netherlands).

    See the full article here .

    Please help promote STEM in your local schools.
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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 8:54 am on December 12, 2015 Permalink | Reply
    Tags: ALMA, , , ,   

    From CfA: “Planetary Influences on Young Stellar Disks” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    December 11, 2015

    1
    False-color images of the gas (left) and dust (right) disks around the young stellar object DoAr44. The results show that the size of the gas ring is much smaller than the dust ring (dotted line), and support a picture in which orbiting planets have swept out the ring.
    ALMA: van der Marel et al.

    A newborn star typically has a disk of gas and dust from which planets develop as the dust grains collide, stick together and grow. Stars older than about five million years lack evidence for these disks, however, suggesting that by this age most of the disk material has either been converted into planets or smaller bodies, accreted onto the star, or dispersed from the system. Transition disks bridge this period in disk evolution: They have not yet been disbursed, and warmed by the star, can be detected at infrared or millimeter wavelengths. Their infrared colors can be used to characterize their properties. They often show inner dust cavities, which astronomers have sometimes interpreted as evidence of the presence of planets that have cleared out their orbits.

    The models of planet-disk interactions, however, indicate that dust cavities are only an indirect consequence of planet clearing. What actually seems to occur is that the planet creates a gap in the gas, and the gas distribution at its outer edges then traps the small dust grains and produces a dust ring that is frequently asymmetric. There is some uncertainty in this picture because other mechanisms could produce a dust cavity or dust ring, including selective evaporation of dust grains by starlight, or instabilities in the dust ring itself. Determining the gas density inside the cavity can help to distinguish between these mechanisms.

    CfA astronomer Sean Andrews and his colleagues used the ALMA millimeter-wavelength telescope array to study transition disks in four relatively nearby young stars.

    ALMA Array
    ALMA

    This powerful new facility can measure dimensions in these disks as small as twenty-four astronomical units (one AU is the average distance of the Earth from the Sun), and can do so for both the small dust grains and the warm gas. In all four disks the scientists were able to model the gas distribution. They found that the gas cavity was as much as three times smaller than the dust cavity, and that the gas density inside the cavity drops by at least a factor of one thousand compared to the surface density. The results strongly suggest that the cavities were indeed produced by orbiting planets.
    Reference(s):

    Resolved Gas Cavities in Transitional Disks Inferred from CO Isotopologs With ALMA,” N. van der Marel, E.F. van Dishoeck, S. Bruderer, S.M. Andrews, K.M. Pontoppidan, G.J. Herczeg, T. van Kempen, and A. Miotello, A&A, in press (2015).

    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 7:53 am on December 11, 2015 Permalink | Reply
    Tags: ALMA, , , , Two New Worlds?   

    From SA: “Did The Solar System Just Gain Two New Worlds?” 

    Scientific American

    Scientific American

    December 10, 2015
    Caleb A. Scharf

    A pair of scientific papers suggest that the ALMA observatory may have detected 2 new ‘planet-scale’ objects associated with the outer realms of the solar system. But should we be awed or skeptical?

    1
    NASA/JPL-Caltech

    When scientific papers come with titles like “The serendipitous discovery of a possible new solar system object with ALMA” and “ALMA discovers the most distant object of the solar system” it’s easy to feel a little excitement in the air.

    The Atacama Large Millimeter/submillimeter Array (ALMA) is a near-brand-new astronomical observatory perched at over 5,000 meters altitude in Chile’s Atacama desert.

    ALMA Array
    ALMA Array

    It has an unprecedented combination of sensitivity and spatial resolution for studying wavelengths of electromagnetic radiation that can probe some of the otherwise dimmest, coolest, and most enshrouded objects in the universe.

    Now, two reports by Vlemmings et al. and Liseau et al. claim that early ALMA data may have serendipitously detected not just one, but two previously unseen objects in the outer solar system. One of these, nicknamed ‘Gna’ is suggested by the researchers to most likely be a body of anywhere from 200 to 800 kilometers in diameter lurking somewhere between 12 and 25 times further from the Sun than the Earth (i.e. 12 to 25 astronomical units, AU).

    This would make Gna a substantial addition to the outer solar system, orbiting within Neptune’s orbit, and a possible new Centaur object. However, the estimates of distance and size are subject to enormous uncertainty since the detection is based around three ‘epochs’ of data separated by a few months (only two of which detected the object), during which the mystery object moved across the sky by an amount consistent with something in proximity to the solar system. An alternative explanation would be a much larger body – perhaps a giant planet or even a brown dwarf – some 2,500 to 4,000 AU distant.

    The other reported detection is perhaps even more mysterious. With observations some 10 months apart the researchers claim that ALMA has detected a sub-millimeter thermal radiation source that is very close on the sky to the Alpha Centauri AB system (within arcseconds of angle) and apparently moves in near synchrony with those stars as they shift across the sky due to parallax from our viewpoint and their own proper motion through the galaxy.

    2
    α Centauri and β Centauri, with Proxima circled. Skatebiker

    But, if this object was simply a part of the Alpha Centauri system it would have to have a size in the stellar mass range (perhaps a few tenths the mass of the Sun) and that would make it bright enough in visible light to have been noticed long ago – which it never has been. So it probably isn’t a star.

    The explanation favored by the authors of the report is that this is either a super-Earth sized planet or a super-cool brown dwarf – somewhere between 300 AU and 20,000 AU from the Sun respectively – and therefore part of the solar system. Although they do also seem to suggest that it could be more like an Extreme Trans-Neptunian Object (ETNO), which might not be so massive.

    The possible existence of a super-Earth or brown dwarf in the outer reaches of our solar system, is, to say the least, quite a proposition. Other research has certainly suggested the possibility, but without any direct observational support. If correct it would be a hugely significant discovery about the grand architecture of our planetary system and offer countless new insights to the history and nature of planet formation and evolution.

    However, it may be a bit early to crack open the champagne. These data are fascinating but also puzzling. For example, this hypothesized object would be in an orbit strongly inclined with respect to the primary plane of the solar system (the ecliptic) by some -42 degrees – raising the question of how that could occur. Furthermore, the likelihood of the first detection of a massive planetary companion to our solar system also aligning with the direction to the very nearest stars, and in being close step with their apparent motion in the sky, seems a little odd.

    Of course, coincidences do happen. And since ALMA is a new observatory the first data will tend to be acquired around known targets, so if you’re going to discover new things they will often appear close to familiar things. But this set of circumstances raise at least a question over whether there is something more mundane going on to explain these discoveries. For example, with the processing of the data from this brand-new radio telescope and its ongoing shakedown.

    One thing is certain though. It’s moments like these that the potential for wonder in the universe can stop us all in our tracks.

    See the full article here .

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    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

     
  • richardmitnick 9:19 am on December 7, 2015 Permalink | Reply
    Tags: ALMA, ALMA Detects Most Tenuous Molecular Gas Ever Observed, , ,   

    From ALMA: “ALMA Detects Most Tenuous Molecular Gas Ever Observed” 

    ESO ALMA Array
    ALMA

    07 December 2015

    Valeria Foncea
    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 467 6258

    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

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

    Tel: +81 422 34 3630

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

    Richard Hook
    Public Information Officer, ESO

    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
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) discovered the most tenuous molecular gas ever observed. They detected the absorption of radio waves by gas clouds in front of bright celestial objects. This radio shadow revealed the composition and the conditions of diffuse gas in the Milky Way galaxy.

    To calibrate its systems, ALMA looks at objects emitting strong radio waves. On rare occasions, the signals from distant calibrator sources have specific radio frequencies absorbed out of them by foreground gas. This process is similar to how a piece of tinted glass casts a colored shadow when light passes through it. These absorption features contain valuable information about the intervening gas clouds that absorb the radio signals. However, the number of known molecular absorption systems seen in millimeter and submillimeter waveband has been very limited: only about 30 in the Milky Way galaxy and a limited number in other galaxies.

    To find more absorption systems, a research team including Ryo Ando (a graduate student at the University of Tokyo), Kotaro Kohno (a professor at the University of Tokyo), and Hiroshi Nagai (a project associate professor at the National Astronomical Observatory of Japan) collected the calibration data from the ALMA Data Archive.

    1
    Figure 1. Illustration of absorption systems. Calibrator sources have flat radio spectra. Molecules in the intervening gas clouds absorb radio waves at specific frequencies determined by the type of molecules. Credit: R. Ando (The University of Tokyo), ESO/José Francisco Salgado

    2
    Figure 2. Radio image (upper) and spectra (bottom) of J1717-337 taken with ALMA. Thanks to its high sensitivity, ALMA detects many absorption lines caused by various molecules such as HCN and HCO+. Credit: ALMA (ESO/NAOJ/NRAO), R. Ando (The University of Tokyo)

    By examining data from 36 calibrator sources, the team discovered three new absorption systems and confirmed one previously known system. For one calibrator source, J1717-337, they found absorptions caused by ten different molecules, such as C3H2, CS, and HCS+. In addition, the team found absorption signals caused by HCO molecules for two of the calibrator sources, J1717-337 and NRAO530. The HCO absorption signal is very rare; only three other examples are known in the Milky Way galaxy.

    Absorption systems allow researchers to investigate very tenuous gas clouds. A gas cloud too diffuse to emit sufficient radio waves to be detected can still absorb enough radio waves to produce a detectable radio shadow. The team estimated that the amount of HCO in the cloud backlit by NRAO530 is only half that of other known systems. This shows that it is one of the most diffuse gas clouds ever discovered in the Milky Way galaxy. Even though astronomers assume that tenuous gas clouds account for a considerable fraction of the total mass of the Milky Way galaxy, very little is known about them.

    The absorption signals help us determine the environment around the foreground gas clouds. HCO molecules are thought to be formed in special environments full of intense ultraviolet light from giant young stars. The diffuse gas clouds backlit by J1717-337 and NRAO530 show chemical composition similar to the gas in active star forming regions, indicating that the diffuse gas is bathed in strong ultraviolet light. Astronomers believe that ultraviolet light affects the properties of diffuse clouds. The HCO absorption systems found by ALMA provide an opportunity to verify that idea.

    This research revaluates the importance of the ALMA calibration data. Usually the calibration data are considered supplementary, but this research shows that the calibration data themselves may contain significant scientific discoveries. The data for the more than 1000 calibration sources stored in the ALMA Data Archive are publicly available, and ALMA continues to take calibration data as part of normal observations. For astronomers, the Archive is a gold mine with the potential to yield more absorption systems or other unexpected mysteries of the Universe.

    This observation result was published as Ando et al. New detections of Galactic molecular absorption systems toward ALMA calibrator sources in the Publications of the Astronomical Society of Japan, issued in December 2015.

    Links

    New Detections of Galactic Molecular Absorption Systems toward ALMA Calibrator Sources by R. Ando, K. Kohno, Y. Tamura, T. Izumi, H. Umehata, H. Nagai

    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 3:48 pm on December 4, 2015 Permalink | Reply
    Tags: ALMA, , , Monster baby galaxies,   

    From ALMA via phys.org: “ALMA spots monstrous baby galaxies cradled in dark matter” 

    phys.org

    ESO ALMA Array
    ALMA

    December 4, 2015

    1
    Example of Monstrous Galaxies. On the left is the image taken at sub-millimeter wavelengths with ASTE. It looks like there is one bright monstrous galaxy. In the center is an image taken at the same sub-millimeter wavelengths, but this time using the new radio telescope facility ALMA. With 60 times better resolution and 10 times better sensitivity, we can see that actually there are 3 monstrous galaxies close together. On the right is the same region photographed in visible light by the Subaru Telescope. We can see that not all of the monstrous galaxies show up in this picture, or at the least that some of them must be very faint. Credit: ALMA (ESO/NAOJ/NRAO), NAOJ, H. Umehata (The University of Tokyo)

    Astronomers discovered a nest of monstrous baby galaxies 11.5 billion light-years away using the Atacama Large Millimeter/submillimeter Array (ALMA). The young galaxies seem to reside at the junction of gigantic filaments in a web of dark matter. These findings are important for understanding how monstrous galaxies like these are formed and how they evolve in to huge elliptical galaxies.

    We are living in a relatively quiet period in the history of the Universe. Ten billion years ago, long before the Sun and Earth were formed, areas of the Universe were inhabited by monstrous galaxies with star formation rates hundreds or thousands of times what we observe today in the Milky Way galaxy. There aren’t any monstrous galaxies left in the modern Universe, but astronomers believe that these young galaxies matured into giant elliptical galaxies which are seen in the modern Universe.

    Current galaxy formation theories predict that these monstrous galaxies form in special environments where dark matter is concentrated. But up until now it has been difficult to determine the positions of active star forming galaxies with enough precision to actually test this prediction. Part of the problem is that monstrous star-forming galaxies are often obscured in dust, making them difficult to observe in visible light. Dusty galaxies do emit strong radio waves with submillimeter wavelengths, but radio telescopes typically have not had the resolution needed to pin-point individual galaxies.

    To search for monstrous galaxies, the research team led by Hideki Umehata (a postdoctoral fellow of the Japan Society for the Promotion of Science staying at the European Southern Observatory, Germany), Yoichi Tamura (an assistant professor at the University of Tokyo), and Kotaro Kohno (a professor at the University of Tokyo) used ALMA to make extensive observations of a small part of the sky called SSA22 in the constellation Aquarius (the Water-Bearer).

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    Monstrous galaxies are thought to preferentially always be born at the centers of the web like structures formed by young galaxies. Credit: ALMA (ESO/NAOJ/NRAO)

    Before their ALMA observations, the team searched for baby galaxies in SSA22 with ASTE, a 10-m submillimeter telescope operated by NAOJ.

    NAOJ ASTE 10 meter telescope
    NAOJ ASTE telescope

    While the sensitivity and resolution was not sufficient to be sure, in the ASTE images they could see indications that there might be a cluster of monstrous galaxies. With ten times better sensitivity and 60 times better resolution, ALMA enabled astronomers to pinpoint the locations of nine monstrous galaxies in SSA22.

    The team compared the positions of these galaxies with the location of a cluster of young galaxies 11.5 billion light-years from Earth in SSA22 which had been studied in visible light by the Subaru Telescope, operated by the National Astronomical Observatory of Japan (NAOJ).

    NAOJ Subaru Telescope
    NAOJ Subaru Telescope interior
    NAOJ/Subaru

    The shape of the cluster observed by the Subaru Telescope indicates the presence of a huge 3D web of invisible dark matter. This dark matter filamentary structure is thought to be a progenitor of large scale structures in the Universe. One of the best known examples of large scale structure in the modern Universe is the cosmic Great Wall, a gigantic filamentary structure spanning over 500 million light-years. The filamentary structure in SSA22 could be called a proto-Great Wall.

    The team found that their young monstrous galaxies seemed to be where located right at the intersection of the dark matter filaments. This finding supports the model that monstrous galaxies form in areas where dark matter is concentrated. And since modern large elliptical galaxies are simply monstrous galaxies which have mellowed with age, they too must have originated at nexuses in the large scale structure.

    This result is a very important step for a comprehensive understanding of the relation between the dark matter distribution and monstrous galaxies. The team will continue its extensive search for monstrous galaxies to look back even farther into the early history of the Universe to study the evolution of the large scale structure.

    More information: This observation result was published as Umehata et al. “ALMA Deep Field in SSA22: A concentration of dusty starbursts in a z=3.09 protocluster core” in the Astrophysical Journal Letters, issued on Dec. 4, 2015.

    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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