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  • richardmitnick 1:25 pm on November 11, 2014 Permalink | Reply
    Tags: , , , , , Radio Astronomy   

    From ALMA: “ALMA Finds Best Evidence Yet for Galactic Merger in Distant Protocluster “ 

    ESO ALMA Array
    ALMA

    Tuesday, 11 November 2014
    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
    Email: 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
    Email: hiramatsu.masaaki@nao.ac.jp

    Nestled among a triplet of young galaxies more than 12.5 billion light-years away is a cosmic powerhouse: a galaxy that is producing stars nearly 1,000 times faster than our own Milky Way. This energetic starburst galaxy, known as AzTEC-3, together with its gang of calmer galaxies may represent the best evidence yet that large galaxies grow from the merger of smaller ones in the early Universe, a process known as hierarchical merging.

    conc
    Artist’s impression of the protocluster observed by ALMA. It shows the central starburst galaxy AzTEC-3 along with its labeled cohorts of smaller, less active galaxies. New ALMA observations suggest that AzTEC-3 recently merged with another young galaxy and that the whole system represents the first steps toward forming a galaxy cluster. | Credit: B. Saxton (NRAO/AUI/NSF)

    An international team of astronomers observed these remarkable objects with the Atacama Large Millimeter/submillimeter Array (ALMA).

    “The ALMA data reveal that AzTEC-3 is a very compact, highly disturbed galaxy that is bursting with new stars at close to its theoretically predicted maximum limit and is surrounded by a population of more normal, but also actively star-forming galaxies,” said Dominik Riechers, an astronomer and assistant professor at Cornell University in Ithaca, New York, and lead author on a paper published today (Nov. 11) in the Astrophysical Journal. “This particular grouping of galaxies represents an important milestone in the evolution of our Universe: the formation of a galaxy cluster and the early assemblage of large, mature galaxies.”

    In the early Universe, starburst galaxies like AzTEC-3 were forming new stars at a monstrous pace fueled by the enormous quantities of star-forming material they devoured and by merging with other adolescent galaxies. Over billions of years, these mergers continued, eventually producing the large galaxies and clusters of galaxies we see in the Universe today.

    Evidence for this hierarchical model of galaxy evolution has been mounting, but these latest ALMA data show a strikingly clear picture of the all-important first steps along this process when the Universe was only 8 percent of its current age.

    “One of the primary science goals of ALMA is the detection and detailed study of galaxies throughout cosmic time,” said Chris Carilli, an astronomer with the National Radio Astronomy Observatory in Socorro, New Mexico. “These new observations help us put the pieces together by showing the first steps of a galaxy merger in the early Universe.”

    AzTEC-3, which is located in the direction of the constellation Sextans, is what astronomers refer to as a submillimeter galaxy, since it shines brightly in that portion of the spectrum, but is remarkably dim at optical and infrared wavelengths. This is due to light from its stars being absorbed by dust in the star-forming environments of the galaxy and then reemitted by the dust at far-infrared wavelengths. As this light travels across the cosmos, it becomes stretched due to the expansion of the Universe, so by the time it arrives at Earth, the far-infrared light has shifted to the submillimeter/millimeter portion of the spectrum.

    sf
    Image of the star-forming gas in AzTEC-3 (upper right) and its neighbor LBG-1 (lower left) observed by ALMA. This portion of the ALMA data only identifies galaxies at the distance of AzTEC-3. | Credit: ALMA (NRAO/NAOJ/ESO); B. Saxton (NRAO/AUI/NSF)

    ALMA, with its remarkable sensitivity and high resolving power, was able to observe this system at these wavelengths in unprecedented detail. It also was able to study, for the first time, the star-forming gas in three additional, extremely distant members of an emerging galactic protocluster.

    The ALMA data revealed that the three smaller, more normal galaxies are indeed producing stars from their gas at a relatively calm and steady pace. Unlike its neighbors, however, AzTEC-3 is burning through star-forming fuel at breakneck speed. Indeed, AzTEC-3 appears to form more new stars each day than our Milky Way galaxy forms in an entire year — outpacing the normal galaxies in its proximity by about a factor of 100.

    The researchers also observed very little rotation in AzTEC-3′s dust and gas — suggesting that something had disrupted its motion. Taken together, these two characteristics are strong indications that AzTEC-3 recently merged with another galaxy.

    three
    Combined data from Japan’s Subaru telescope and ALMA of the AzTEC-3 region; the circled regions are members of this protocluster, which were previously highlighted by Subaru. The ALMA data are highlighted with arrows. | Credit: Subaru/NASA/JPL, P. Capak (SSC/Caltech); B. Saxton (NRAO/AUI/NSF)

    NAOJ Subaru TelescopeNAOJ Subaru Telescope interior
    NAOJ/Subaru

    “AzTEC-3 is currently undergoing an extreme, but short-lived event,” said Riechers. “This is perhaps the most violent phase in its evolution, leading to a star formation activity level that is very rare at its cosmic epoch.”

    The astronomers believe that AzTEC-3 and the other nearby galaxies appear to be part of the same system, but are not yet gravitationally bound into a clearly defined cluster. This is why the astronomers refer to them collectively as a protocluster.

    The starburst galaxy was originally observed with and named after the AzTEC millimeter-wavelength camera, which was installed at the time on the James Clerk Maxwell Telescope, a single-dish radio telescope located on Mauna Kea, Hawaii. Only with ALMA has it become possible to understand the nature of this exceptional galaxy and those in its immediate environment.

    James Clerk Maxwell Telescope
    James Clerk Maxwell Telescope interior
    James Clerk Maxwell Telescope

    See the full article here.

    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 6:53 am on November 11, 2014 Permalink | Reply
    Tags: , , ATCA, , , Radio Astronomy, University of Western Australia   

    From UWA: “Astronomers dissect the aftermath of a supernova” 

    UWA

    University of Western Australia

    Tuesday, 11 November 2014
    Dr Giovana Zanardo (ICRAR – UWA)
    Ph: +61 8 6488 7765 E: Giovanna.Zanardo@gmail.com M: +61 414 531 081
    Professor Lister Staveley-Smith (ICRAR Science Director – UWA)
    Ph: +61 8 6488 4550 E: Lister.Staveley-smith@icrar.org M: +61 425 212 592
    Pete Wheeler (Media Contact, ICRAR)
    Ph: +61 8 6488 7771 E: Pete.Wheeler@icrar.org M: +61 423 982 018
    David Stacey (UWA Media Manager)
    Ph: +61 8 6488 7977 E: David.Stacey@uwa.edu.au

    In research published today in the Astrophysical Journal, an Australian-led team of astronomers has used radio telescopes in Australia and Chile to see inside the remains of a supernova.

    The supernova, known as SN1987A, was first seen by observers in the southern hemisphere in 1987 when a giant star suddenly exploded at the edge of a nearby dwarf galaxy called the Large Magellanic Cloud.

    1987
    Description :This image shows the remnant of Supernova 1987A seen in light of very different wavelengths. ALMA data (in red) shows newly formed dust in the centre of the remnant. Hubble (in green) and Chandra (in blue) data show the expanding shock wave.
    Date 6 January 2014, 16:15:00
    Source http://www.eso.org/public/images/eso1401a/
    Author ALMA (ESO/NAOJ/NRAO)/A. Angelich. Visible light image: the NASA/ESA Hubble Space Telescope. X-Ray image: The NASA Chandra X-Ray Observatory

    In the two-and-a-half decades since then the remnant of Supernova 1987A has continued to be a focus for researchers worldwide, providing a wealth of information about one of the Universe’s most extreme events.

    PhD candidate Giovanna Zanardo, at The University of Western Australia node of the International Centre for Radio Astronomy Research, led the team that used the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile’s Atacama Desert and the Australia Telescope Compact Array (ATCA) in New South Wales to observe the remnant at wavelengths spanning the radio to the far infrared.

    ALMA Array
    ALMA

    Australian Telescope Compact Array
    ATCA

    “By combining observations from the two telescopes we’ve been able to distinguish radiation being emitted by the supernova’s expanding shock wave from the radiation caused by dust forming in the inner regions of the remnant,” she said.

    “This is important because it means we’re able to separate out the different types of emission we’re seeing and look for signs of a new object which may have formed when the star’s core collapsed. It’s like doing a forensic investigation into the death of a star.

    “Our observations with the ATCA and ALMA radio telescopes have shown signs of something never seen before, located at the centre or the remnant. It could be a pulsar wind nebula, driven by the spinning neutron star, or pulsar, which astronomers have been searching for since 1987.

    “It’s amazing that only now, with large telescopes like ALMA and the upgraded ATCA, we can peek through the bulk of debris ejected when the star exploded and see what’s hiding underneath.”

    More research published recently in the Astrophysical Journal also attempts to shine a light on another long-standing mystery surrounding the supernova remnant. Since 1992 the radio emission from one side of the remnant has appeared ‘brighter’ than the other.

    In an effort to solve this puzzle, Dr Toby Potter, another researcher from ICRAR’s UWA node has developed a detailed three-dimensional simulation of the expanding supernova shockwave.

    “By introducing asymmetry into the explosion and adjusting the gas properties of the surrounding environment, we were able to reproduce a number of observed features from the real supernova such as the persistent one-sidedness in the radio images”, Dr Potter said.

    The time-evolving model shows that the eastern (left) side of the expanding shock front expands more quickly than the other side, and generates more radio emission than its weaker counterpart. This effect becomes even more apparent as the shock collides into the equatorial ring, as observed in Hubble Space Telescope images of the supernova.

    NASA Hubble Telescope
    NASA Hubble schematic
    NASA/ESA Hubble

    “Our simulation predicts that over time the faster shock will move beyond the ring first. When this happens, the lop-sidedness of radio asymmetry is expected to be reduced and may even swap sides,” Dr Potter said.

    “The fact that the model matches the observations so well means that we now have a good handle on the physics of the expanding remnant and are beginning to understand the composition of the environment surrounding the supernova – which is a big piece of the puzzle solved in terms of how the remnant of SN1987A formed.”

    Further Information:

    ICRAR is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.

    Original publication details:

    Spectral and Morphological Analysis of the Remnant of Supernova 1987a with ALMA & ATCA G. Zanardo, L. Staveley-Smith, R. Indebetouw et al. Published in the in the Astrophysical Journal November 10th, 2014. Pre-print paper available at: http://arxiv.org/abs/1409.7811 and http://iopscience.iop.org/0004-637X/796/2/82 after 8am EST, November 10th.

    See the full article here.

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  • richardmitnick 5:35 pm on November 10, 2014 Permalink | Reply
    Tags: , , , , Radio Astronomy,   

    From SKA: “Kenya, 8 African states plan US $1.9 billion telescope “ 

    SKA Square Kilometer Array

    SKA

    November 05, 2014
    No Writer Credit

    Nine African countries including Kenya have agreed to strengthen their cooperation in radio astronomy research.

    two
    Kenya’s Longonot Earth station: The scientists also discussed how Kenya can participate in the construction and use of the station to co-host the largest radio telescope in the world.

    Delegates attending a two day Square Kilometer Array (SKA) Senior Officials meeting (SOM) in Nairobi recently arrived at a consensus to formalize their engagement through a Memorandum of Understanding.

    The partner countries represented in the meeting include: South Africa, Mozambique, Namibia, Mauritius, Ghana, Madagascar, Zambia, Botswana and host Kenya.

    The meeting attended by policy makers and space scientists discussed how Kenya can participate in the construction and use of the Longonot earth station to co-host the largest radio telescope in the world. The SKA project is to be implemented in three phases and is expected to commence in 2016 and be completed by 2024. The cost of the construction of the telescope is estimated to be about 1.5billion Euros (Kshs 170 billion or US $ 1.9 billion).

    The draft MOU is expected to be finalized and ratified by the member countries during forthcoming SKA meetings. The meeting also discussed the SKA Africa Readiness Strategy and joint implementation plan and cost estimates for partner states in hosting the African Very Long Baseline Interferometry Network (AVN) and SKA dishes.

    The meetings objective was to consolidate Africa’s support and strategize on how best to make maximum use of this opportunity to lead in global science and position Kenya as a regional center for Basic Space Science.

    During the official opening of the meeting, Education, Science and Technology Principal Secretary Prof. Jacob Kaimenyi noted that this partnership has effectively enhanced awareness around the requirements for hosting radio astronomy instrumentation and the associated benefits that could be derived in making such commitments. He noted that the SKA is expected to bring notable benefits and large capital investments including new job opportunities, increased business opportunity for local industries during and after the construction.

    Prof. Kaimenyi also said that, the Government has created and is implementing an Science Technology and Innovation (ST&I) policy framework to support the country’s Vision 2030 by devoting resources to scientific research, technical capabilities of the workforce, and in raising the quality of teaching science and technology in learning institutions. He informed the meeting that the Science Technology and Innovation Act of 2013 provides for allocation of at least 2 percent of the country’s Gross Domestic Product (GDP) for research and development (R&D). He added that the Ministry of Education, Science and Technology is in the process of establishing a National Research Fund to realize the 2 percent provision.

    See the full article here.

    SKA Banner

    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

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  • richardmitnick 3:48 pm on November 6, 2014 Permalink | Reply
    Tags: , , , , , Radio Astronomy   

    From ALMA: “Revolutionary ALMA Image Reveals Planetary Genesis” 

    ESO ALMA Array
    ALMA

    Wednesday, 05 November 2014

    Catherine Vlahakis
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 9 75515736
    Email: cvlahaki@alma.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

    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

    A new image from ALMA, the Atacama Large Millimeter/submillimeter Array, reveals extraordinarily fine detail that has never been seen before in the planet-forming disc around a young star. ALMA’s new high-resolution capabilities were achieved by spacing the antennas up to 15 kilometers apart [1]. This new result represents an enormous step forward in the understanding of how protoplanetary discs develop and how planets form.

    ALMA has obtained its most detailed image yet showing the structure of the disc around HL Tau [2], a million-year-old Sun-like star located approximately 450 light-years from Earth in the constellation of Taurus. The image exceeds all expectations and reveals a series of concentric and bright rings, separated by gaps.

    f1
    Fig. 1 (top): This is the sharpest image ever taken by ALMA — sharper than is routinely achieved in visible light with the NASA/ESA Hubble Space Telescope. It shows the protoplanetary disc surrounding the young star HL Tauri. These new ALMA observations reveal substructures within the disc that have never been seen before and even show the possible positions of planets forming in the dark patches within the system. Credit: ALMA (ESO/NAOJ/NRAO).

    f2
    Fig. 2 (left): This is a composite image of the young star HL Tauri and its surroundings using data from ALMA (enlarged in box at upper right) and the NASA/ESA Hubble Space Telescope (rest of the picture). This is the first ALMA image where the image sharpness exceeds that normally attained with Hubble. Credit: ALMA (ESO/NAOJ/NRAO)/NASA/ESA

    f3
    Fig. 3 (right): This image compares the size of the Solar System with HL Tauri and its surrounding protoplanetary disc. Although the star is much smaller than the Sun, the disc around HL Tauri stretches out to almost three times as far from the star as Neptune is from the Sun. Credit: ALMA (ESO/NAOJ/NRAO)

    “These features are almost certainly the result of young planet-like bodies that are being formed in the disc. This is surprising since such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image,” said Stuartt Corder, ALMA Deputy Director.

    “When we first saw this image we were astounded at the spectacular level of detail. HL Tauri is no more than a million years old, yet already its disc appears to be full of forming planets. This one image alone will revolutionize theories of planet formation,” explained Catherine Vlahakis, ALMA Deputy Program Scientist and Lead Program Scientist for the ALMA Long Baseline Campaign.

    Such a resolution can only be achieved with the long baseline capabilities of ALMA and provides astronomers with new information that is impossible to collect with any other facility, even the Hubble Space Telescope. “The logistics and infrastructure required to place antennas at such distant locations required an unprecedented coordinated effort for the international expert team of engineers and scientists” said ALMA Director, Pierre Cox. “These long baselines fulfill one of ALMA’s major objectives and mark an impressive technological, scientific and engineering milestone”, celebrated Cox.

    Stars like HL Tau and our own Sun form within clouds of gas and dust that collapse under gravity. Over time, the surrounding dust particles stick together, growing into sand, pebbles, and larger-size rocks, which eventually settle into a thin disc where asteroids, comets, and planets form. Once these planetary bodies acquire enough mass, they dramatically reshape the structure of the disc, fashioning rings and gaps as the planets sweep their orbits clear of debris and shepherd dust and gas into tighter and more confined zones.

    f4
    Fig. 4: This is an artist’s impression of a young star surrounded by a protoplanetary disc in which planets are forming. Using ALMA’s 15-kilometre baseline astronomers were able to make the first detailed image of a protoplanetary disc, which revealed the complex structure of the disc. Concentric rings of gas, with gaps indicating planet formation, are visible in this artist’s impression and were predicted by computer simulations. Now these structures have been observed by ALMA for the first time. Credit: ESO/L. Calçada

    In the visible, HL Tau is partly obscured by the massive cloud of dust and gas that surrounds it. ALMA operates in such a way that it can see through the cloud and study the processes right at the center. This new ALMA image provides the clearest evidence to date that not only does this process occur, but also that it is faster than previously thought.

    The investigation of these protoplanetary discs is essential to our understanding of how Earth formed in the Solar System. Observing the first stages of planet formation around HL Tauri may show us how our own planetary system may have looked more than four billion years ago, when it formed.

    Notes

    [1] Since September 2014 ALMA has been observing the Universe using its longest ever baselines, with antennas separated by up to 15 kilometers. This Long Baseline Campaign will continue until 1 December 2014. The baseline is the distance between two of the antennas in the array. As a comparison, other facilities operating at millimeter wavelengths provide antennas separated by no more than two kilometers. The maximum possible ALMA baseline is 16 kilometers. Future observations at shorter wavelengths will achieve even higher image sharpness.

    [2] The structures are seen with a resolution of just five times the distance from the Sun to the Earth. This corresponds to an angular resolution of about 35 milliarcseconds — better than what is routinely achieved with the NASA/ESA Hubble Space Telescope.

    See the full article, with videos, here.

    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 8:50 pm on November 4, 2014 Permalink | Reply
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    From SETI: “Workshop Ponders Challenges of Communicating Across the Cosmos” 


    SETI Institute

    November 03 2014
    Science Contact:
    Douglas Vakoch, SETI Institute
    Chair, “Communicating Across the Cosmos” Workshop
    dvakoch@seti.org
    +1-650-960-4514
    Skype: dougvakoch

    http://communicating.seti.org

    David Black, SETI Institute
    CEO
    dblack@seti.org
    +1 650-960-4550

    Media Contact:
    Seth Shostak, SETI Institute
    Press Officer, and Senior Astronomer
    +1 650 960-4530
    sshostak@seti.org

    When astronomers conducting the Search for Extraterrestrial Intelligence (SETI) find other cultures in the universe, could we understand their messages? How can we craft a reply that intelligence on other planets would comprehend? To tackle these questions, the SETI Institute will convene the international workshop Communicating Across the Cosmos: How Can We Make Ourselves Understood by Other Civilizations in the Galaxy? on November 10-11, 2014, at its headquarters in Mountain View, California.

    “As we search for a universal language to communicate with civilizations beyond Earth, where should we start? Math? Pictures? Something else?” asked Douglas Vakoch, Director of Interstellar Message Composition at the SETI Institute and organizer of the workshop. “It may be much more difficult to create an understandable message than we’ve thought in the past, and our workshop faces those challenges head on. “Recommendations from the meeting will be incorporated into the final report of the International Academy of Astronautics’ Study Group on Interstellar Message Construction.

    disc

    “In the past few years, astronomers have shown that most stars have planets, so there could be many worlds where life has arisen,” said David Black, President and CEO of the SETI Institute. “If we discover life beyond Earth, especially technological life, it would have a profound effect on humanity. We need to take concrete steps now to plan for first contact. The SETI Institute just held a workshop on Non-Human Communication that examined the complex languages used by other life forms on this planet. The insights that we gain into the fundamental aspects of communication from those types of studies inform us potentially about communication with non-terrestrial life forms.”

    At the workshop, speakers from six countries will draw on disciplines ranging from astronomy and mathematics, to anthropology and linguistics, as they debate the best ways to create meaningful messages. “As we explore ways to communicate with intelligence in the cosmos, we need to do so intelligently,” explained Pierre Schwob, Vice Chairman of the SETI Institute’s Board of Trustees.

    The SETI Institute searches for radio signals from other civilizations with the Allen Telescope Array in northern California, but does not transmit signals to other worlds. “We’re also seeing increased interest within the international SETI community in actively transmitting messages, trying to elicit a response from other intelligence that may be out there,” said Vakoch. “Before we can do that, we need to be clear about what we would say, and how we would say it—the same questions we’ll grapple with in this meeting.”

    Allen Telescope Array
    Allen Telescope Array

    This workshop is closed to the public, but videos of all talks will be posted on the SETI Institute’s Youtube channel after the workshop. Media representatives who would like to attend or interview speakers should contact Douglas Vakoch, dvakoch@seti.org, phone +1-650-960-4514, Skype dougvakoch. Only queries from media representatives will be answered.

    Visit the workshop website for more information at http://communicating.seti.org

    See the full article here.

    SETI Institute – 189 Bernardo Ave., Suite 100
    Mountain View, CA 94043
    Phone 650.961.6633 – Fax 650-961-7099
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  • richardmitnick 8:15 am on November 4, 2014 Permalink | Reply
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    From SKA via Contributoria: “Is there life out there? How the world’s largest telescope could tell us everything.” 

    SKA Square Kilometer Array

    SKA

    From Contributoria

    cont

    October 2014
    Katiem

    It’s rare to meet someone who claims to have the best job in the world but the architect of what will become the largest scientific instrument on the planet believes he has it. Tim Cornwell is part of the team, based at Jodrell Bank in the UK, who are building the Square Kilometer Array (SKA), a series of linked radio dishes that collectively will create the biggest and most sensitive radio telescope in the world. Once completed it will have a total collecting area of over 1 million square meters and will be so sensitive that it would be able to detect an airport radar signal on a planet tens of light years away. Cornwell, who is lead architect on the telescope, has spent his career working in the field and his passion for radio astronomy is clear, “The thrill of building radio telescopes and seeing things people have never seen before is just amazing” he says. The SKA will be built across two sites, in Australia and South Africa, areas deliberately chosen for their ‘radio quietness’, where the lack of population means a corresponding lack of noise and therefore lower risk of interference from radio devices.

    teles

    For non-scientists radio astronomy may not immediately spark excitement but the aims of the SKA are relevant to everyone. Using the SKA scientists will address some of the greatest unanswered questions of our time, including, how do galaxies form? What is dark energy? Was [Albert] Einstein right about gravity? And perhaps most alluring, are we alone in the Universe? As SKA project scientist Tyler Bourke puts it, “We will have the sensitivity and the view of the sky to detect leakage equivalent to normal TV signals or radio stations from other planets up to a significant distance. It comes to the point where we should be able to hear something.” In that typical understated fashion common to scientists Bourke goes on to say that if the telescope doesn’t pick up anything then “it causes us some problems”, in effect if the SKA doesn’t hear anything we would know that it’s highly likely we are the only complex lifeform in the Universe. Of course looked at the other way, as suggested on their website “the detection of any extraterrestrial signals would forever change the perception of humanity in the Universe.”

    Given the magnitude of the scientific questions it will seek to tackle, by the time it’s switched on the SKA will likely be as much of a household name as the Large Hadron Collider. Before then though there is significant work to be done.

    Although the SKA headquarters are at Jodrell Bank in the UK, the project itself has 11 participating member countries and coordinating input and feedback from all participants is clearly a mammoth task. The first phase of the project is to finalise the detail of the design of the telescope, this also has to consider questions such as how they will manage, move and process the huge amount of data a telescope of this size will generate. Processing the data will be in itself a massively complex task and as part of this initial design phase, the team has been talking to processor manufacturers like Intel and Nvidia about what may be possible. They’re also in discussions with Amazon about the possibility of using the Amazon cloud to do their processing. Whatever the final solution Tim Cornwell provided some context for the size of the task they face, “We have to go up a huge amount in processing scale, the fastest telescope in the world at the moment is LOFAR and we’re going to go about a 1000 times faster than that.” It has also been described as having the processing power of about one hundred million PCs. The sheer volume of data that will be created by the telescope will mean it will be impossible for them to keep it all. Cornwell explained how they will handle the data, “We’ll process it into science products, like images of the sky, and then we’ll throw away the raw data. If you didn’t do it this way it’d cost hundreds of millions of Euros to run it every year.”

    Another logistical challenge is how they will power the SKA. An instrument of this size will require significant power to operate and in order to extract and process the data. And while a major factor as to why the selected sites were chosen was due to their remote, quiet location, in Australia, this remoteness brings with it the challenge of being off grid.

    Once the final design in agreed, in 2018, construction will begin, this will take place in two phases, but by 2020 they will be able to begin some initial work, what they refer to as “early science”. By 2024 the telescope should be completed.

    Even at this relatively early stage in the life of the SKA scientists from around the world are excited about the possibilities and are currently submitting their ideas and plans for the experiments they’d like to carry out using it. And although the big high-level questions have been set out, in common with many large-scale exploration projects, it’s likely that it will discover something that hadn’t even been considered. When you look at it that way it’s easy to understand why this team of passionate scientists and radio astronomers talk about having the best jobs in the world.

    See the full article here.

    SKA Banner

    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

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  • richardmitnick 5:29 pm on October 29, 2014 Permalink | Reply
    Tags: , , , , Radio Astronomy,   

    From SKA: “Australian Square Kilometre Array telescope takes shape in WA outback” 

    SKA Square Kilometer Array

    SKA

    13 Oct 2014
    Gian De Poloni

    A project to build one of the world’s most powerful radio astronomy telescopes is taking shape in Western Australia’s outback.

    The $160 million Australian Square Kilometre Array Pathfinder [ASKAP] is being built in a radio quiet area of WA’s Murchison region, about a four-hour drive from the port city of Geraldton.

    three
    Photo: Three ASKAP telescopes are trained towards the sky east of Geraldton. (Alex Cherney)

    The project has seen the installation of 36 huge antenna dishes on Boolardy Station, which will eventually work together to survey large areas of sky to help scientists understand how galaxies have formed and evolved.

    CSIRO scientist Lisa Harvey-Smith said although only six of the dishes were active, the images that had been taken so far were remarkable.

    “The latest picture we’ve taken has almost 2000 galaxies in it, which is incredible,” she said.

    “It’s kind of a wide field image of the sky.

    “Once we’ve got 36 telescopes, we’ll be able to do a huge survey of the entire night’s sky and see millions of new galaxies, black holes and things in the very distant universe that no one’s ever seen before.”

    She said the question of what exactly the telescope will be able to see in distant space was a complete mystery.

    “The discovery potential of this telescope is quite amazing,” she said.

    “Even now, we’ve been able to look at galaxies that are actually older than our Earth – which is a pretty incredible thing – and look into the distant universe to search for galaxies that were actually around billions of years ago and may not exist anymore.”

    Dr Harvey-Smith said the giant dishes were picking up radio waves being emitted from objects in space.

    “Our eyes can’t see radio waves, so the data that we get is just boring ones and zeros, but we actually use clever computer algorithms and a super computer that’s based in Perth to make the images into real optical type images that we can see,” she said.

    Telescope will view area 200 time size of moon

    Project director Antony Schinckel said images produced so far were stunning.

    “The thing about ASKAP is it’s a completely new type of telescope – it’s never been built before – so a lot of this very early work is simply understanding exactly how to use it,” he said.

    “Many of our staff said ‘look, it’s not worth trying to do much with just the six dishes because we won’t be able to see much’, but they’ve been completely shown to be wrong.

    “Trying to predict ahead to what we’re going to see with 36 at the full capability is really hard but we’ll be able to very quickly map really big areas of the sky and by really big, I mean in a single snapshot we’ll be able to see an area around about 200 times the size of the full moon.

    “There are still huge holes in our knowledge of how our universe evolved, where galaxies come from, how planets form and we expect ASKAP will be able to really help us answer a lot of that.”

    Dr Schinckel estimated it would cost about $10 million a year to keep the project going.

    “We’ve had good support from the Government over the last few years and we believe the Government does see the positive impacts of these sorts of projects,” he said.

    “There’s the pure science side, there’s the very tight international collaboration aspect, there’s the technology spin off, there’s training of engineers and scientists who may or may not stay on in astronomy but may go on to work in other fields.”

    ASKAP is viewed as a precursor to the future $1.9 billion Square Kilometre Array, which will be built in both the Murchison and South Africa in 2018, with input in design and funding coming from 11 countries.

    The SKA is expected to be the largest and most capable radio telescope.

    what
    Photo: This wide shot image taken from the ASKAP telescope over 12 hours shows distant galaxies. (Supplied: CSIRO)

    telescope
    ASKAP telescope image Photo: This wide shot image taken from the ASKAP telescope over 12 hours shows distant galaxies. (Supplied: CSIRO)

    Murchison ideal location for project

    Dr Harvey-Smith said the isolation of the Murchison region made it the perfect place for the project.

    “If you could imagine trying to listen for a mouse under your floorboards hearing tiny scratching noises, you don’t want to be playing the radio very loudly in the background,” she said.

    “It’s the same type of thing with the radio telescopes.

    “We’re looking for tiny, tiny signals incredibly week from galaxies billions of light years away.
    Under a brilliant night sky, ASKAP telescopes are pointed to the night stars Photo: Raw data from the ASKAP telescopes totals about 100 terabytes per second. (Alex Cherney)

    “They’re so weak we have to amplify them millions of times with specialist electronic equipment.”

    Dr Schinckel said the communications infrastructure in place to support the telescope was unfathomable.

    “The raw data rate we get from the telescopes is about 100 terabytes per second,” he said.

    “To put that in context, that’s about the entire traffic of the internet all around the world in one second.

    “Luckily the super computers we have on site can very quickly reduce the data back to a more manageable volume of around about 10 gigabytes per second.

    “The sheer volume of that and the speed of which that raw data comes in is truly astounding.”

    Dr Harvey Smith said she could control the telescope from the comfort of her lounge room.

    “As one of the research scientists, I can access the telescope from Sydney – from my house, on my laptop,” she said.

    “We just send signals through the internet and tell the telescope what to do.

    “It’s pretty amazing that we can have a giant international scientific facility with very few people actually out there on the site.”

    It is hoped the entire network of dishes will be fully operational by March 2016.

    See the full article here.

    SKA Banner

    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

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  • richardmitnick 3:45 pm on October 29, 2014 Permalink | Reply
    Tags: , , , , , Radio Astronomy   

    From ALMA: “Planet-forming Lifeline Discovered in a Binary Star System” 

    ESO ALMA Array
    ALMA

    Wednesday, 29 October 2014

    Anne Dutrey
    Laboratoire d’Astrophysique de Bordeaux
    University Bordeaux/CNRS – France
    Tel: +33 5 57 776140
    Email: Anne.Dutrey@obs.u-bordeaux1.fr

    Emmanuel DiFolco
    Laboratoire d’Astrophysique de Bordeaux
    University Bordeaux/CNRS France
    Tel: +33 5 57 776136
    Email: Emmanuel.Difolco@obs.u-bordeaux1.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: +1 434.242.9559
    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

    For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disc toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. The results are published in the journal Nature on October 30, 2014.

    A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France and CNRS used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A [1]. This object is only a few million years old and lies about 450 light-years from Earth in the constellation of Taurus (The Bull).

    Like a wheel in a wheel, GG Tau-A contains a large, outer disc encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

    sytar
    Fig. 1: This artist’s impression shows the dust and gas around the double star system GG Tauri-A. Researchers using ALMA have detected gas in the region between two discs in this binary system. This may allow planets to form in the gravitationally perturbed environment of the binary. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. Credit: ESO/L. Calçada

    While observing these structures with ALMA, the team made the exciting discovery of gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two [2].

    “Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other,” explains Dutrey. “These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

    Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disc is a prerequisite for planet formation. If the feeding process into the inner disc now seen with ALMA occurs in other multiple-star systems the findings introduce a vast number of new potential locations to find exoplanets in the future.

    The first phase of exoplanet searches was directed at single-host stars like the Sun [3]. More recently it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

    Emmanuel Di Folco, co-author of the paper, concludes: “Almost half the Sun-like stars were born in binary systems. This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.”

    Notes

    [1] GG Tau-A is part of a more complex multiple-star system called GG Tauri. Recent observations of GG Tau-A using the VLTI have revealed that one of the stars — GG Tau Ab, the one not surrounded by a disc — is itself a close binary, consisting of GG Tau-Ab1 and GG Tau-Ab2. This introduced a fifth component to the GG Tau system.

    ESO VLT Interferometer
    ESO VLTI

    [2] An earlier result with ALMA showed an example of a single star with material flowing inwards from the outer part of its disc.

    [3] Because orbits in binary stars are more complex and less stable, it was believed that forming planets in these systems would be more challenging than around single stars.

    More Information

    This research was presented in a paper entitled Planet formation in the young, low-mass multiple stellar system GG Tau-A” by A. Dutrey et al., to appear in the journal Nature.

    The team is composed of Anne Dutrey (University Bordeaux/CNRS, France), Emmanuel Di Folco (University Bordeaux/CNRS), Stephane Guilloteau (University Bordeaux/CNRS), Yann Boehler (University of Mexico, Michoacan, Mexico), Jeff Bary (Colgate University, Hamilton, USA), Tracy Beck (Space Telescope Science Institute, Baltimore, USA), Hervé Beust (IPAG, Grenoble, France), Edwige Chapillon (University Bordeaux/IRAM, France), Fredéric Gueth (IRAM, Saint Martin d’Hères, France), Jean-Marc Huré (University Bordeaux/CNRS), Arnaud Pierens (University Bordeaux/CNRS), Vincent Piétu (IRAM), Michal Simon (Stony Brook University, USA) and Ya-Wen Tang (Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan).

    See the full article here.

    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

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  • richardmitnick 1:26 pm on October 22, 2014 Permalink | Reply
    Tags: , , , , , , Radio Astronomy   

    From NASA Goddard: “NASA-led Study Sees Titan Glowing at Dusk and Dawn” 

    NASA Goddard Banner

    October 22, 2014
    Nancy Neal-Jones 301-286-0039
    nancy.n.jones@nasa.gov
    Elizabeth Zubritsky 301-614-5438
    Goddard Space Flight Center, Greenbelt, Md.
    elizabeth.a.zubritsky@nasa.gov

    New maps of Saturn’s moon Titan reveal large patches of trace gases shining brightly near the north and south poles. These regions are curiously shifted off the poles, to the east or west, so that dawn is breaking over the southern region while dusk is falling over the northern one.

    two
    High in the atmosphere of Titan, large patches of two trace gases glow near the north pole, on the dusk side of the moon, and near the south pole, on the dawn side. Brighter colors indicate stronger signals from the two gases, HNC (left) and HC3N (right); red hues indicate less pronounced signals.
    Image Credit: NRAO/AUI/NSF

    The pair of patches was spotted by a NASA-led international team of researchers investigating the chemical make-up of Titan’s atmosphere.

    “This is an unexpected and potentially groundbreaking discovery,” said Martin Cordiner, an astrochemist working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the lead author of the study. “These kinds of east-to-west variations have never been seen before in Titan’s atmospheric gases. Explaining their origin presents us with a fascinating new problem.”

    The mapping comes from observations made by the Atacama Large Millimeter/submillimeter Array (ALMA), a network of high-precision antennas in Chile. At the wavelengths used by these antennas, the gas-rich areas in Titan’s atmosphere glowed brightly. And because of ALMA’s sensitivity, the researchers were able to obtain spatial maps of chemicals in Titan’s atmosphere from a “snapshot” observation that lasted less than three minutes.

    ALMA Array
    ALMA Array

    Titan’s atmosphere has long been of interest because it acts as a chemical factory, using energy from the sun and Saturn’s magnetic field to produce a wide range of organic, or carbon-based, molecules. Studying this complex chemistry may provide insights into the properties of Earth’s very early atmosphere, which may have shared many chemical characteristics with present-day Titan.

    In this study, the researchers focused on two organic molecules, hydrogen isocyanide (HNC) and cyanoacetylene (HC3N), that are formed in Titan’s atmosphere. At lower altitudes, the two molecules appear concentrated above Titan’s north and south poles. These findings are consistent with observations made by NASA’s Cassini spacecraft, which has found a cloud cap and high concentrations of some gases over whichever pole is experiencing winter on Titan.

    NASA Cassini Spacecraft
    NASA/Cassini

    The surprise came when the researchers compared the gas concentrations at different levels in the atmosphere. At the highest altitudes, the gas pockets appeared to be shifted away from the poles. These off-pole locations are unexpected because the fast-moving winds in Titan’s middle atmosphere move in an east–west direction, forming zones similar to Jupiter’s bands, though much less pronounced. Within each zone, the atmospheric gases should, for the most part, be thoroughly mixed.

    The researchers do not have an obvious explanation for these findings yet.

    “It seems incredible that chemical mechanisms could be operating on rapid enough timescales to cause enhanced ‘pocket’’ in the observed molecules,” said Conor Nixon, a planetary scientist at Goddard and a coauthor of the paper, published online today in the Astrophysical Journal Letters. “We would expect the molecules to be quickly mixed around the globe by Titan’s winds.”

    At the moment, the scientists are considering a number of potential explanations, including thermal effects, previously unknown patterns of atmospheric circulation, or the influence of Saturn’s powerful magnetic field, which extends far enough to engulf Titan.

    Further observations are expected to improve the understanding of the atmosphere and ongoing processes on Titan and other objects throughout the solar system.

    NASA’s Astrobiology Program supported this work through a grant to the Goddard Center for Astrobiology, a part of the NASA Astrobiology Institute. Additional funding came from NASA’s Planetary Atmospheres and Planetary Astronomy programs. ALMA, an international astronomy facility, is funded in Europe by the European Southern Observatory, in North America by the U.S. National Science Foundation in cooperation with the National Research Council of Canada and the National Science Council of Taiwan, and in East Asia by the National Institutes of Natural Sciences of Japan in cooperation with the Academia Sinica in Taiwan.

    See the full article here.

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA

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  • richardmitnick 9:23 pm on October 16, 2014 Permalink | Reply
    Tags: , , , , , Radio Astronomy   

    From NRAO: “Milky Way Ransacks Nearby Dwarf Galaxies, Stripping All Traces of Star-Forming Gas” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    October 15, 2014
    Contact: Charles E. Blue, Public Information Officer
    (434) 296-0314; cblue@nrao.edu

    Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia, along with data from other large radio telescopes, have discovered that our nearest galactic neighbors, the dwarf spheroidal galaxies, are devoid of star-forming gas, and that our Milky Way Galaxy is to blame.

    mw

    These new radio observations, which are the highest sensitivity of their kind ever undertaken, reveal that within a well-defined boundary around our Galaxy, dwarf galaxies are completely devoid of hydrogen gas; beyond this point, dwarf galaxies are teeming with star-forming material.

    The Milky Way Galaxy is actually the largest member of a compact clutch of galaxies that are bound together by gravity. Swarming around our home Galaxy is a menagerie of smaller dwarf galaxies, the smallest of which are the relatively nearby dwarf spheroidals, which may be the leftover building blocks of galaxy formation. Further out are a number of similarly sized and slightly misshaped dwarf irregular galaxies, which are not gravitationally bound to the Milky Way and may be relative newcomers to our galactic neighborhood.

    “Astronomers wondered if, after billions of years of interaction, the nearby dwarf spheroidal galaxies have all the same star-forming ‘stuff’ that we find in more distant dwarf galaxies,” said astronomer Kristine Spekkens, assistant professor at the Royal Military College of Canada and lead author on a paper published in the Astrophysical Journal Letters.

    Previous studies have shown that the more distant dwarf irregular galaxies have large reservoirs of neutral hydrogen gas, the fuel for star formation. These past observations, however, were not sensitive enough to rule out the presence of this gas in the smallest dwarf spheroidal galaxies.

    By bringing to bear the combined power of the GBT (the world’s largest fully steerable radio telescope) and other giant telescopes from around the world, Spekkens and her team were able to probe the dwarf galaxies that have been swarming around the Milky Way for billions of years for tiny amounts of atomic hydrogen.

    “What we found is that there is a clear break, a point near our home Galaxy where dwarf galaxies are completely devoid of any traces of neutral atomic hydrogen,” noted Spekkens. Beyond this point, which extends approximately 1,000 light-years from the edge of the Milky Way’s star-filled disk to a point that is thought to coincide with the edge of its dark matter distribution, dwarf spheroidals become vanishingly rare while their gas-rich, dwarf irregular counterparts flourish.

    There are many ways that larger, mature galaxies can lose their star-forming material, but this is mostly tied to furious star formation or powerful jets of material driven by supermassive black holes. The dwarf galaxies that orbit the Milky Way contain neither of these energetic processes. They are, however, susceptible to the broader influences of the Milky Way, which itself resides within an extended, diffuse halo of hot hydrogen plasma.

    The researchers believe that, up to a certain distance from the galactic disk, this halo is dense enough to affect the composition of dwarf galaxies. Within this “danger zone,” the pressure created by the million-mile-per-hour orbital velocities of the dwarf spheroidals can actually strip away any detectable traces of neutral hydrogen. The Milky Way thus shuts down star formation in its smallest neighbors.

    “These observations therefore reveal a great deal about size of the hot halo and about how companions orbit the Milky Way,” concludes Spekkens.

    See the full article here.

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    NRAO ALMA
    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

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