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  • richardmitnick 9:44 am on May 25, 2016 Permalink | Reply
    Tags: ALMA, ALMA Reveals Footprints of Baby Planets in a Gas Disk, , , ,   

    From ALMA: “ALMA Reveals Footprints of Baby Planets in a Gas Disk” 

    ALMA Array

    ALMA

    24 May 2016
    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: nicolas.lira@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: +1 202 236 6324
    E-mail: cblue@nrao.edu

    New analysis of ALMA data for HL Tauri provides yet more firm evidence of baby planets around the star. Researchers uncovered two gaps in the gas disk around the star. The locations of these gaps in the gas match the locations of gaps in the dust found in the ALMA high resolution image taken in 2014. This discovery supports the idea that planets form in much shorter timescales than previously thought and prompts a reconsideration of alternative planet formation scenarios.

    In November 2014, ALMA released a startling image of HL Tauri and its dust disk. This image, the sharpest ever taken for this kind of object, clearly depicts several gaps in the dust disk around the star.

    1
    Figure 1. ALMA image of the dust disk around HL Tauri. Credit: ALMA (ESO/NAOJ/NRAO)

    Astronomers have not yet reached a definitive answer for what makes the gaps in the dust disk. Because these disks are the sites of planet formation, some suggest that infant planets are the key; the dark gaps are carved by planets forming in the disk that attract or sweep away the dust along their orbits.

    But others doubt the planet explanation because HL Tauri is very young, estimated to be only about a million years, and classical studies indicate that it takes more than tens of millions of years for planets to form from small dust. Those researchers propose other possible mechanisms to form the gaps: changes in the dust size through coalescence or destruction; or the formation of dust due to gas molecules freezing.

    More data was needed to determine which theory is correct. We know that the disks around young stars contain gas in addition to the dust. In fact, in general the amount of gas is 100 times larger than that of dust. The research team led by Dr. Hsi-Wei Yen at Academia Sinica Institute of Astronomy and Astrophysics in Taiwan and Professor Shigehisa Takakuwa at Kagoshima University, Japan, focused on the distribution of gas in the disk to better understand the true nature of the disk. If the dust gaps are caused by the variance of the dust properties, that wouldn’t directly affect the gas, so no gaps would be seen in the gas distribution. If on the other hand, the gaps in the dust are caused by the gravity of forming planets, the gravity would be expected to created gaps in the gas as well.

    Even with ALMA’s unprecedented sensitivity, it was not easy to reveal the distribution of gas in the disk. The team extracted the emissions from HCO+ gas molecules in the publicly available 2014 ALMA Long Baseline Campaign data and summed up the emissions in rings around the star to increase the effective sensitivity. This novel data analysis technique yielded the sharpest image ever of the gas distribution around a young star.

    The image of HCO+ distribution reveals at least two gaps in the disk, at the radii of 28 and 69 astronomical units. “To our surprise, these gaps in the gas overlap with the dust gaps,” said Yen, the lead author of the paper that appeared in the Astrophysical Journal Letters. “This supports the idea that the gaps are the footprints left by baby planets.” The fact that the gaps in the dust and the gas match-up implies that the amount of material in the gaps likely decreases. This disfavors some of the theories that tried to explain the gaps solely by changes in the dust particles. A decrease in the amount of material in the gaps supports the planet formation theory, in spite of HL Tauri’s young age. “Our results indicate that planets start to form much earlier than what we expected.” Yen added.

    2
    Figure 2. HCO+ gas (blue) and dust (red) distributions in the disk around HL Tauri. The ellipses show the locations of the gaps. Credit: ALMA (ESO/NAOJ/NRAO), Yen et al.

    3
    Figure 3. Artist’s concept of HL Tauri. The star is surrounded by the disk (shown in red) and thick envelope. The star ejects a bipolar collimated jet. Credit: ASIAA

    The team also found that the gas density is high enough to harbor an infant planet around the inner gap. Comparing the structure of the inner gap to theoretical models, the team estimates the planet has a mass 0.8 times that of Jupiter.

    On the other hand, the origin of the outer gap is still unclear. The team suggested the possible existence of a planet 2.1 times more massive than Jupiter, but the present research cannot eliminate the possibility that the gap is made by the drag between the dust particles and the gas. To solve this question, more data are needed.

    “Our research clearly demonstrates that applying new data analysis techniques to existing data can uncover important facts, further increasing ALMA’s already high scientific potential,” commented Takakuwa. “Applying the same method to the datasets for other young stars, we expect to construct a systematic model of planet formation.”

    Additional information

    These observation results were published as Yen et al. Gas Gaps in the Protoplanetary Disk around the Young Protostar HL Tau in the Astrophysical Journal Letters, issued in April 2016.

    The research team members are:

    Hsi-Wei Yen (Academia Sinica Institute of Astronomy and Astrophysics, Taiwan), Hauyu Baobab Liu (European Southern Observatory, Germany), Pin-Gao Gu, Naomi Hirano, Chin Fei Lee (Academia Sinica Institute of Astronomy and Astrophysics, Taiwan), Evaria Puspitaningrum (Institut Teknologi Bandung, Indonesia) and Shigehisa Takakuwa (Kagoshima University, Japan).

    This research is supported by the Ministry of Science and Technology, Taiwan.

    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 3:15 pm on May 17, 2016 Permalink | Reply
    Tags: ALMA, , , HR 8799, ,   

    From ALMA: “Cometary Belt around Distant Multi-Planet System Hints at Hidden or Wandering Planets” 

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array

    ALMA

    17 May 2016
    Valeria Foncea

    Education and Public Outreach Officer

    Joint ALMA Observatory

    Santiago, Chile

    Tel: +56 2 467 6258

    Cell: +56 9 75871963
    Email: valeria.foncea@alma.cl

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

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

    Masaaki Hiramatsu

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

    Tel: +81 422 34 3630

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

    1
    ALMA image of dusty cometary ring around HR 8799, the only star where multiple planets have been imaged. The new data suggest the planets either migrated or another undiscovered planet is present. The zoom-in portion of the image, taken with ESO’s Very Large Telescope, shows the location of the known planets in this system in relation to a graphical representation of the central star. Credit: Booth et al., ALMA (NRAO/ESO/NAOJ); A. Zurlo, et al
    ___________________________________________________________

    Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the first high-resolution image of the cometary belt (a region analogous to our own Kuiper belt) around HR 8799, the only star where multiple planets have been imaged directly.

    Kuiper Belt. Minor Planet Center
    Kuiper Belt. Minor Planet Center

    The shape of this dusty disk, particularly its inner edge, is surprisingly inconsistent with the orbits of the planets, suggesting that either they changed position over time or there is at least one more planet in the system yet to be discovered.

    “This data really allow us to see the inner edge of this disk for the first time,” explains Mark Booth from Pontificia Universidad Católica de Chile and lead author of the study. “By studying the interactions between the planets and the disk, this new observation shows that either the planets that we see have had different orbits in the past or there is at least one more planet in the system that is too small to have been detected.”

    The disk, which fills a region 150 to 420 times the Sun-Earth distance, is produced by the ongoing collisions of cometary bodies in the outer reaches of this star system. ALMA was able to image the emission from millimeter-size debris in the disk; according to the researchers, the small size of these dust grains suggests that the planets in the system are larger than Jupiter. Previous observations with other telescopes at shorter wavelengths did not detect this discrepancy in the disk. It is not clear if this difference is due to the low resolution of the previous observations or because different wavelengths are sensitive to different grain sizes, which would be distributed slightly differently.

    HR 8799 is a young star approximately 1.5 times the mass of the Sun located 129 light-years from Earth in the direction of the constellation Pegasus.

    “This is the very first time that a multi-planet system with orbiting dust is imaged, allowing for direct comparison with the formation and dynamics of our own Solar System,” explains Antonio Hales, co-author of the study from the National Radio Astronomy Observatory in Charlottesville, Virginia.

    Additional information

    These results were published in the Monthly Notices of the Royal Astronomical Society titled Resolving the Planetesimal Belt of HR 8799 with ALMA by Booth et al., May 2016.
    Preprint: http://arxiv.org/abs/1603.04853

    The research team was composed by Mark Booth ([1], [2]), Andrés Jordán ([1], [3]), Simón Casassus ([2], [4]), Antonio S. Hales ([5], [6]), William R. F. Dent ([5]), Virginie Faramaz ([1]), Luca Matrà ([7], [8]), Denis Barkats ([9]), Rafael Brahm ([1], [3]) Jorge Cuadra ([1], [2]).

    [1] Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Santiago, Chile
    [2] Millennium Nucleus “Protoplanetary Disks”
    [3] Millennium Institute of Astrophysics, Vicuña Mackenna 4860, Santiago, Chile
    [4] Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
    [5] Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago, Chile
    [6] National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia, 22903-2475, USA
    [7] Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
    [8] European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago, Chile
    [9] Harvard University, 60 Garden Street, Cambridge, MA 02138, USA

    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 1:35 pm on May 16, 2016 Permalink | Reply
    Tags: , ALMA, , , Discovery of Methanol in a Planetary Birthplace   

    From AAS NOVA: “Discovery of Methanol in a Planetary Birthplace” 

    AASNOVA

    Amercan Astronomical Society

    16 May 2016
    Susanna Kohler

    1
    Artist’s illustration of a protoplanetary disk. The chemistry of a protoplanetary disk determines what molecules are incorporated into a newly forming planet’s atmosphere. [ESO/L. Calçada]

    Data from the Atacama Large Millimeter/submillimeter Array (ALMA) has recently revealed the first detection of gas-phase methanol, a derivative of methane, in a protoplanetary disk. This milestone discovery is an important step in understanding the conditions for planet formation that can lead to life-supporting planets like Earth.

    Planetary Chemistry

    One major goal in the study of exoplanets is to find planets that orbit in their host stars’ habitable zones, a measure that determines whether the planet receives the right amount of sunlight to support liquid water. But there’s another crucial element in the formation of a life-supporting planet: chemistry.

    To understand the chemistry of newly born planets, we need to study protoplanetary disks — because it’s from these that young planets form. The elements and molecules contained in these dusty disks are what initially make up the atmospheres of planets forming within the disks.

    2
    The Atacama Large Millimeter/submillimeter Array under the southern sky. [ESO/B. Tafreshi]

    The Hunt for Complexity

    The detection of complex molecules in protoplanetary disks is an important milestone, because complex molecules are necessary to build the correct chemistry to support life. Unfortunately, detecting these molecules is very difficult, requiring observations with both high spatial resolution and high sensitivity. Thus far, though we’ve observed elements and simple molecules in protoplanetary disks, detections of complex molecules have been elusive — with only one success before now.

    Luckily, we now have an observatory up to the challenge! ALMA’s unprecedented spatial resolution and sensitivity has recently allowed a team of scientists led by Catherine Walsh (Leiden University) to observe gas-phase methanol in a protoplanetary disk for the first time. This detection was made in the disk around the young star TW Hya, and it represents one of the largest molecules that has ever been observed in a disk to date.

    3

    Locating Ices

    Since TW Hya’s disk has temperatures of less than ~100K (-173°C), we would expect most of the disk’s methanol to be frozen. The gas-phase methanol observed by Walsh and collaborators was likely released from a larger reservoir of frozen methanol residing on dust grains in the disk. The peak of the methanol emission was detected from a ring located about 30 AU out from the central star, which suggests that the larger dust grains in the disk — located in the inner 50 AU — may host the bulk of the disk ice reservoir.

    Walsh and collaborator’s important detection opens a window into studying complex organic chemistry during planetary system formation. This stepping stone can help us to better understand the conditions when Earth formed and what we should look for in the search for life-supporting planets.
    Citation

    Science paper:
    FIRST DETECTION OF GAS-PHASE METHANOL IN A PROTOPLANETARY DISK
    Catherine Walsh et al 2016 ApJ 823 L10. doi:10.3847/2041-8205/823/1/L10

    See the full article here .

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  • richardmitnick 11:13 am on May 5, 2016 Permalink | Reply
    Tags: ALMA, , , , ,   

    From ALMA: “ALMA Measures Mass of Black Hole with Extreme Precision” 

    ALMA Array

    ALMA

    05 May 2016

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

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

    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

    1
    Combined image of NGC 1332 shows the central disk of gas surrounding the supermassive black hole at the center of the galaxy. New ALMA observations traced the motion of the disk, providing remarkably precise measurements of the black hole’s mass: 660 million times the mass of our Sun. The main image is from the Carnegie-Irvine Galaxy Survey. The box in the upper left is from the Hubble Space Telescope and shows the galaxy’s central region in infrared light and the dusty disk appears as a dark silhouette. The ALMA image, upper right box, shows the rotation of the disk, enabling astronomers to calculate its mass. The red region in the ALMA image represents emission that has been redshifted by gas rotating away from us; the blue represents blue-shifted gas rotating toward us. The range of colors represent rotational speeds up to 500 kilometers per second. Credit: A. Barth (UC Irvine), ALMA (NRAO/ESO/NAOJ); NASA/ESA Hubble; Carnegie-Irvine Galaxy Survey.

    3
    DSS image of lenticular galaxy NGC 1332 and part of elliptical galaxy NGC 1331. Celestial Atlas.

    Supermassive black holes, some weighing millions to billions of times the mass of the Sun, dominate the centers of their host galaxies. To determine the actual mass of a supermassive black hole, astronomers must measure the strength of its gravitational pull on the stars and clouds of gas that swarm around it.

    Using the Atacama Large Millimeter/submillimeter Array (ALMA), a team of astronomers has delved remarkably deep into the heart of a nearby elliptical galaxy to study the motion of a disk of cold interstellar gas encircling the supermassive black hole at its center. These observations provide one of the most accurate mass measurements to date for a black hole outside of our Galaxy, helping set the scale for these cosmic behemoths.

    To obtain this result, Aaron Barth, an astronomer at the University of California, Irvine (UCI), and lead author on a paper published* in the Astrophysical Journal Letters, and his team used ALMA to measure the speed of carbon monoxide gas in orbit around the black hole at the center of NGC 1332, a massive elliptical galaxy approximately 73 million light-years from Earth in the direction of the southern constellation Eridanus.

    “Measuring the mass of a black hole accurately is very challenging, even with the most powerful telescopes on Earth or in space,” Barth said. “ALMA has the revolutionary ability to observe disks of cold gas around supermassive black holes at small enough scales that we can clearly distinguish the black hole’s influence on the disk’s rotational speed.”

    The ALMA observations reveal details of the disk’s structure on the order of 16 light-years across. They also measure the disk’s rotation well within the estimated 80 light-year radius of the black hole’s “sphere of influence” – the region where the black hole’s gravity is dominant.

    Near the disk’s center, ALMA observed the gas traveling at more than 500 kilometers per second. By comparing these data with simulations, the astronomers calculated that the black hole at the center of NGC 1332 has a mass 660 million times greater than our Sun, plus or minus ten percent. This is about 150 times the mass of the black hole at the center of the Milky Way, yet still comparatively modest relative to the largest black holes known to exist, which can be many billions of solar masses.

    ALMA’s close-in observations were essential, the researchers note, to avoid confounding the black hole measurement with the gravitational influence of other material – stars, clouds of interstellar gas, and dark matter – that comprises most of the galaxy’s overall mass.

    “This black hole, though individually massive, accounts for less one percent of the mass of all the stars in the galaxy,” noted Barth. “Most of a galaxy’s mass is in the form of dark matter and stars, and on the scale of an entire galaxy, even a giant black hole is just a tiny speck in the center. The key to detecting the influence of the black hole is to observe orbital motion on such small scales that the black hole’s gravitational pull is the dominant force.” This observation is the first demonstration of this capability for ALMA.

    Astronomers use various techniques to measure the mass of black holes. All of them, however, rely on tracing the motion of objects as close to the black hole as possible. In the Milky Way, powerful ground-based telescopes using adaptive optics can image individual stars near the galactic center and precisely track their trajectories over time. Though remarkably accurate, this technique is feasible only within our own Galaxy; other galaxies are too distant to distinguish the motion of individual stars.

    To make similar measurements in other galaxies, astronomers either examine the aggregate motion of stars in a galaxy’s central region, or trace the motion of gas disks and mega-masers — natural cosmic radio sources.

    Previous studies of NGC 1332 with ground- and space-based telescopes gave wildly different estimates for the mass of this black hole, ranging from 500 million to 1.5 billion times the mass of the Sun.

    The new ALMA data confirm that the lower estimates are more accurate.

    Crucially, the new ALMA observations have higher resolution than any of the past observations. ALMA also detects the emission from the densest, coldest component of the disk, which is in a remarkably orderly circular motion around the black hole.

    Many past measurements made with optical telescopes, including the Hubble Space Telescope, focused on the emission from the hot, ionized gas orbiting in the central region of a galaxy. Ionized-gas disks tend to be much more turbulent than cold disks, which leads to lower precision when measuring a black hole’s mass.

    “ALMA can map out the rotation of gas disks in galaxy centers with even sharper resolution than the Hubble Space Telescope,” noted UCI graduate student Benjamin Boizelle, a co-author on the study. “This observation demonstrates a technique that can be applied to many other galaxies to measure the masses of supermassive black holes to remarkable precision.”

    Additional information

    These results were published* in the Astrophysical Journal Letters as Measurement of the black hole mass in NGC 1332 from ALMA observations at 0.044 arcsecond resolution, by Aaron Barth et al.

    The team is composed of Aaron Barth (University of California, Irvine), Benjamin D. Boizelle (University of California, Irvine), Jeremy Darling (University of Colorado, Boulder), Andrew J. Baker (Rutgers, the State University of New Jersey, Piscataway), David A. Buote (University of California, Irvine), Luis Ho (Kavli Institute of Astronomy and Astrophysics, Peking University, China), and Jonelle L. Walsh (Texas A&M University, College Station).

    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 7:31 pm on April 20, 2016 Permalink | Reply
    Tags: ALMA, , , Dusty doughnut around massive black hole spied for first time, ,   

    From New Scientist: “Dusty doughnut around massive black hole spied for first time” 

    NewScientist

    New Scientist

    20 April 2016
    Shannon Hall

    1
    A dusty doughnut might look like this. NASA/JPL-Caltech

    It won’t taste very good. We have for the first time imaged one of the doughnuts of dust long thought to encircle some supermassive black holes.

    Astronomers think all galaxies are “active” at some point in their lifetimes, meaning that the central supermassive black hole feeds on a circling disc of gas. Although that disc can be so bright that it outshines the entire galaxy, some seem to be obscured by a doughnut-shaped structure of dust and gas, called a “torus.” Yet because the centres of these active galaxies are so distant, a dusty torus has never been seen – until now.

    Santiago Garcia-Burillo of Spain’s Madrid Observatory and his colleagues used a radio telescope array to image the torus of NGC 1068, a galaxy 50 million light years away. Although it is one of the brightest and nearest active galaxies, its torus still appears tens of thousands of times smaller than the moon.

    The discovery required 35 radio dishes on the Atacama Large Millimeter/submillimeter Array (ALMA) perched in the high desert of the Chilean Andes.

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array

    “It’s an absolutely remarkable observation,” says Jack Gallimore of Bucknell University in Lewisburg, Pennsylvania. “It’s a real testament to how much of a powerhouse ALMA is.”

    It should also shed light on a long-standing problem in astrophysics, namely what causes a galaxy to become active, says Gallimore. Although we know that clouds of gas must fall from the galaxy towards the supermassive black hole, it’s not that simple.

    As the gas falls inward, it spins faster, allowing it to reach a circular velocity like Earth’s orbit around the sun. “A cloud would eventually be spinning so fast that it would just achieve a stable orbit around the black hole,” says Gallimore. “So that prevents it from falling in and feeding the black hole.”

    And yet these supermassive black holes actively accrete gas and dust – enough to grow to millions or billions of times the sun’s mass. So if astronomers can see how gas flows through the torus, they are likely to get a better handle on what sparks the black hole feeding frenzy behind an active galaxy.

    Science paper:
    ALMA resolves the torus of NGC 1068: continuum and molecular line emission

    See the full article here .

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  • richardmitnick 3:13 pm on April 14, 2016 Permalink | Reply
    Tags: ALMA, , , , Stanford astrophysicists help discover hidden dwarf dark galaxy   

    From Stanford: “Stanford astrophysicists help discover hidden dwarf dark galaxy” 

    Stanford University Name
    Stanford University

    April 14, 2016
    Bjorn Carey, Stanford News Service
    (650) 725-1944
    bccarey@stanford.edu

    1
    Composite image of the gravitational lens SDP.81 showing the distorted image of the more distant galaxy (red arcs) and the nearby lensing galaxy (blue center object). By analyzing the distortions in the ring, astronomers have determined that a dark dwarf galaxy (data indicated by white dot near left lower arc segment) is lurking nearly 4 billion light-years away. (Credit: Y. Hezaveh; ALMA)

    The study develops a powerful tool for discovering galaxies that are otherwise too distant to observe, and could lead to advances that improve our understanding of dark matter.

    New analysis of an image taken by the Atacama Large Millimeter/submillimeter Array (ALMA) reveals evidence that a dwarf dark galaxy – a tiny halo companion of a much larger galaxy – is lurking nearly 4 billion light-years away.

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array

    This discovery, led by a Stanford astrophysicist and announced today, paves the way for ALMA to find many more such objects, which could help astronomers address important questions on the nature of dark matter.

    In 2014, as part of ALMA’s Long Baseline Campaign, astronomers studied a variety of astronomical objects to test the telescope’s new high-resolution capabilities. One of these experimental images was that of an Einstein ring, which was produced by a massive foreground galaxy bending the light emitted by another galaxy nearly 12 billion light-years away.

    This phenomenon, called gravitational lensing, was predicted by Einstein’s theory of general relativity, and it offers a powerful tool for studying galaxies that are otherwise too distant to observe. It also sheds light on the properties of the nearby lensing galaxy because of the way its gravity distorts and focuses light from more distant objects.

    In a new paper accepted for publication in the Astrophysical Journal, astrophysicist Yashar Hezaveh at Stanford and his team explain how detailed analysis of this image of a galaxy called SDP.81 uncovered signs of a hidden dwarf dark galaxy in the halo of a the more nearby galaxy.

    “We can find these invisible objects in the same way that you can see rain droplets on a window: You know they are there because they distort the image of the background objects,” explained Hezaveh. In the case of a raindrop, the image distortions are caused by refraction, but here similar distortions are generated by the gravitational influence of dark matter, according to Einstein’s theory of relativity.

    Current theories suggest that dark matter, which makes up 80 percent of the mass of the universe, is made of as-yet-unidentified particles that don’t interact with visible light or other forms of electromagnetic radiation. Dark matter does, however, have appreciable mass, so it can be identified by its gravitational influence.

    For their analysis, the researchers harnessed thousands of computers working in parallel for many weeks, including the National Science Foundation’s most powerful supercomputer, Blue Waters, to search for subtle anomalies that had a consistent and measurable counterpart in each “band” of radio data.

    Blue Waters supercomputer at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign
    Cray Blue Waters supercomputer at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign

    From these combined computations, the researchers were able to piece together an unprecedented understanding of the lensing galaxy’s halo, the diffuse and predominantly star-free region around the galaxy, and discovered a distinctive clump, less than one-thousandth the mass of the Milky Way.

    Because of its relationship to the larger galaxy, its estimated mass and lack of an optical counterpart, the astronomers believe this gravitational anomaly may be caused by an extremely faint, dark-matter dominated satellite of the lensing galaxy. According to theoretical projections, most galaxies should be brimming with similar dwarf galaxies and other companion objects. Detecting them, however, has proven challenging. Even in our own Milky Way, astronomers can identify only about 40 of the thousands of satellite dwarfs that are predicted to be present.

    Computer models of the evolution of the universe indicate that if the number of small dark matter clumps around distant galaxies, like the one detected here, is significantly lower than predictions, this would imply that the dark matter particles have a warm temperature.

    Risa Wechsler, an associate professor of physics at Stanford, and graduate student Yao-Yuan Mao used these compter simulations to show that so far this detection is consistent with the predictions of the cold dark matter theoretical model. More observations are needed, however, to definitively rule out the possibility of a warm temperature for dark matter.

    “This detection is very exciting – it shows that we finally have a tool to find these dwarf satellites efficiently in a way that was not possible before,” said Wechsler. “Now we need to look at other galaxies to hopefully find more of these small dark halos to have a statistically significant test of the cold dark matter predictions.”

    The finding is an exciting demonstration of the power of ALMA, said astrophysicist Roger Blandford, the Luke Blossom Professor in the School of Humanities and Science at Stanford, who was involved in the research. “This discovery proves that ALMA can be used to provide valuable new insights into the physics of dark matter.”

    The other Stanford authors on the paper* include Philip Marshall, Warren Morningstar and Laurence Perreault Levasseur. All Stanford authors are also members of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford.

    *Science paper:
    Detection of lensing substructure using ALMA observations of the dusty galaxy SDP.81

    Science team:
    YASHAR D. HEZAVEH1,12 , NEAL DALAL2,3,4,5 , DANIEL P. MARRONE6 , YAO-YUAN MAO1,7 , WARREN MORNINGSTAR1 , DI WEN2 ,
    ROGER D. BLANDFORD1,7 , JOHN E. CARLSTROM8 , CHRISTOPHER D. FASSNACHT9 , GILBERT P. HOLDER10 , ATHOL KEMBALL2 ,
    PHILIP J. MARSHALL7 , NORMAN MURRAY11,13 , LAURENCE PERREAULT LEVASSEUR1 , JOAQUIN D. VIEIRA2 , RISA H. WECHSLER1,7

    Affiliations:

    1 Kavli Institute for Particle Astrophysics and Cosmology and Department
    of Physics, Stanford University, 452 Lomita Mall, Stanford, CA
    94305-4085, USA
    2 Astronomy Department, University of Illinois at Urbana-Champaign,
    1002 W. Green Street, Urbana IL 61801, USA
    3 School of Natural Sciences, Institute for Advanced Study, 1 Einstein
    Drive, Princeton, NJ 08540, USA
    4 Kavli Institute for the Physics and Mathematics of the Universe, TODIAS,
    The University of Tokyo, Chiba, 277-8583, Japan
    5 Department of Chemistry and Physics, University of Kwa-Zulu Natal,
    University Road, Westville, KZN, South Africa
    6 Steward Observatory, University of Arizona, 933 North Cherry Avenue,
    Tucson, AZ 85721, USA
    7 Kavli Institute for Particle Astrophysics and Cosmology and Department
    of Particle Physics and Astrophysics; SLAC National Accelerator
    Laboratory, Menlo Park, CA 94305, USA
    8 Kavli Institute for Cosmological Physics, University of Chicago, 5640
    South Ellis Avenue, Chicago, IL 60637, USA
    9 Department of Physics, University of California, One Shields Avenue,
    Davis, CA 95616, USA
    10 Department of Physics, McGill University, 3600 Rue University,
    Montreal, Quebec H3A 2T8, Canada
    11 CITA, University of Toronto, 60 St. George St., Toronto ON M5S
    3H8, Canada
    12 Hubble Fellow
    13 Canada Research Chair in Astrophysics

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 10:38 am on March 31, 2016 Permalink | Reply
    Tags: ALMA, ALMA's Best Image of a Protoplanetary Disk - TW Hydrae, , , ,   

    From ALMA: “ALMA’s Best Image of a Protoplanetary Disk” 

    ALMA Array

    ALMA

    30 March 2016
    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: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

    Masaaki Hiramatsu

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

    Tel: +81 422 34 3630

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

    ALMA protoplanetary  disk  Sun-like star TW Hydrae.
    ALMA image of the planet-forming disk around the young, Sun-like star TW Hydrae. The inset image (upper right) zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the Sun, suggesting an infant version of our home planet could be emerging from the dust and gas. The additional concentric light and dark features represent other planet-forming regions farther out in the disk. Credit: S. Andrews (Harvard-Smithsonian CfA), ALMA (ESO/NAOJ/NRAO)

    The disks of dust and gas that surround young stars are the formation sites of planets. New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal never-before-seen details in the [protoplanetary] disk around a nearby Sun-like star, including a tantalizing gap at the same distance from the star as the Earth is from the Sun. This structure may mean that an infant version of our home planet, or possibly a more massive super-Earth, is beginning to form there.

    The star, TW Hydrae, is a popular target of study for astronomers because of its proximity to Earth (approximately 175 light-years away) and its status as a veritable newborn (about 10 million years old). It also has a face-on orientation as seen from Earth. This affords astronomers a rare, undistorted view of the complete disk.

    “Previous studies with optical and radio telescopes confirm that this star hosts a prominent disk with features that strongly suggest planets are beginning to coalesce,” said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on a paper published today in Astrophysical Journal Letters. “The new ALMA images show the disk in unprecedented detail, revealing a series of concentric dusty bright rings and dark gaps, intriguing features that suggest a planet with an Earth-like orbit is forming there.”

    Other pronounced gap features are located 3 billion and 6 billion kilometers from the central stars, similar to the distances from the Sun to Uranus and Pluto in our own Solar System. They too are likely the result of particles that came together to form planets, which then swept their orbits clear of dust and gas and shepherded the remaining material into well-defined bands.

    For the new TW Hydrae observations, astronomers imaged the faint radio emission from millimeter-size dust grains in the disk, revealing details on the order of the distance between the Earth and the Sun (about 150 million kilometers). These detailed observations were made possible with ALMA’s high-resolution, long-baseline configuration. When ALMA’s dishes are at their maximum separation, up to 15 kilometers apart, the telescope is able to resolve finer details. “This is the highest spatial resolution image ever of a protoplanetary disk from ALMA, and that won’t be easily beat going forward,” said Andrews [1].

    “TW Hydrae is quite special. It is the nearest known protoplanetary disk to Earth and it may closely resemble our Solar System when it was only 10 million years old,” said co-author David Wilner, also with the Harvard-Smithsonian Center for Astrophysics.

    Earlier ALMA observations of another system, HL Tau, show that even younger protoplanetary disks – a mere 1 million years old – can display similar signatures of planet formation.

    2
    ALMA image of the protoplanetary disc around HL Tauri – This is the sharpest image ever taken by ALMA

    By studying the older TW Hydrae disk, astronomers hope to better understand the evolution of our own planet and the prospects for similar systems throughout the Galaxy.

    The astronomers’ next phase of research is to investigate how common these kinds of features are in disks around other young stars and how they might change with time or environment.

    Note

    [1] The angular resolution of the images of HL Tauri was similar to these new observations, but as TW Hydrae is much closer to Earth, finer details can be seen.

    This research was presented in a paper “Ringed Substructure and a Gap at 1 AU in the Nearest Protoplanetary Disk”, by S.M. Andrews et al., appearing in the Astrophysical Journal Letters.

    The team is composed of Sean M. Andrews (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA), David J. Wilner (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA) , Zhaohuan Zhu (Princeton University, Princeton, New Jersey, USA), Tilman Birnstiel (Max-Planck-Institut für Astronomie, Heidelberg, Germany), John M. Carpenter (Joint ALMA Observatory, Santiago, Chile), Laura M. Pérez (Max-Planck-Institut für Radioastronomie, Bonn, Germany), Xue-Ning Bai (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA), Karin I. Öberg (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA), A. Meredith Hughes (Wesleyan University, Van Vleck Observatory, Middletown, USA), Andrea Isella (Rice University, Houston, Texas, USA) and Luca Ricci (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA).

    Link to science paper.

    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 9:35 am on March 10, 2016 Permalink | Reply
    Tags: ALMA, , , Mysterious Infrared Light from Space Resolved Perfectly   

    From ALMA: “Mysterious Infrared Light from Space Resolved Perfectly” 

    ALMA Array

    ALMA

    10 March 2016
    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: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Artist’s impression of the Cosmic Infrared Background resolved with ALMA
    Artist’s impression of the Cosmic Infrared Background resolved with ALMA. (Right) This diagram shows that the sum of the emissions from the faint objects detected with ALMA reaches the CIB measured with satellite observations. Credit: NAOJ

    A research team using the Atacama Large Millimeter/submillimeter Array (ALMA) has detected the faintest millimeter-wave source ever observed. By accumulating millimeter-waves from faint objects like this throughout the Universe, the team finally determined that such objects are 100% responsible for the enigmatic infrared background light filling the Universe. By comparing these to optical and infrared images, the team found that 60% of them are faint galaxies, whereas the rest have no corresponding objects in optical/infrared wavelengths and their nature is still unknown.

    The Universe looks dark in the parts between stars and galaxies. However, astronomers have found that there is faint but uniform light, called the “cosmic background emission,” coming from all directions. This background emission consists of three main components; Cosmic Optical Background (COB), Cosmic Microwave Background (CMB), and Cosmic Infrared Background (CIB).

    The origins of the first two have already been revealed. The COB comes from a huge number of stars, and the CMB comes from hot gas just after the Big Bang. However, the origin of the CIB was still to be solved. Various research projects, including past ALMA observations, have been conducted, but they could only explain half of the CIB.

    A research team led by a graduate student, Seiji Fujimoto, and an associate professor, Masami Ouchi, at the University of Tokyo, tackled this mysterious infrared background by examining the ALMA data archive. ALMA is the perfect tool to investigate the source of the CIB thanks to its unprecedented sensitivity and resolution.

    They went through the vast amount of ALMA data taken during about 900 days in total looking for faint objects. They also searched the datasets extensively for lensed sources, where huge gravity has magnified the source making even fainter objects visible [1].

    “The origin of the CIB is a long-standing missing piece in the energy coming from the Universe,” said Seiji Fujimoto, now studying at the Institute of Cosmic Ray Research, the University of Tokyo. “We devoted ourselves to analyzing the gigantic ALMA data in order to find the missing piece.”

    Finally, the team discovered 133 faint objects, including an object five times fainter than any other ever detected. The researchers found that the entire CIB can be explained by summing up the emissions from such objects [2].

    What is the nature of those sources? By comparing the ALMA data with the data taken by the Hubble Space Telescope and the Subaru Telescope, the team found that 60% of them are galaxies which can also be seen in the optical/infrared images.

    NASA Hubble Telescope
    NASA/ESA Hubble

    NAOJ Subaru Telescope
    NAOJ/ Subaru

    Dust in galaxies absorbs optical and infrared light and re-emits the energy in longer millimeter waves which can be detected with ALMA.

    “However, we have no idea what the rest of them are. I speculate that they are galaxies obscured by dust. Considering their darkness, they would be very low-mass galaxies.” Masami Ouchi explained passionately. “This means that such small galaxies contain great amounts of dust. That conflicts with our current understanding: small galaxies should contain small amounts of dust. Our results might indicate the existence of many unexpected objects in the distant Universe. We are eager to unmask these new enigmatic sources with future ALMA observations.”.

    Additional information

    These observational results were published as Fujimoto et al. ALMA Census of Faint 1.2 mm Sources Down to ~ 0.02 mJy: Extragalactic Background Light and Dust-poor, High-z Galaxies in the Astrophysical Journal Supplement, issued in December 28, 2015.

    This research is supported by the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan, and KAKENHI Grant-in-Aid for Scientific Research through the Japan Society for the Promotion of Science (JSPS).

    Notes

    [1] See an explanation and video about gravitational lensing.


    Access the video here .

    [2] ALMA detected a part of the CIB with 1 mm wavelengths. The CIB in millimeter and submillimeter waves does not become weak even if the source is located far away. Therefore this wavelength is suitable for looking through the Universe to the most distant parts.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
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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 11:06 am on March 3, 2016 Permalink | Reply
    Tags: ALMA, , ,   

    From ALMA: “ALMA Spots Baby Star’s Growing Blanket” 

    ALMA Array

    ALMA

    01 March 2016
    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: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Protoplanetary disc from ALMA
    Typical protoplanetary disc. ALMA

    Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the first direct observations delineating the gas disk around a baby star from the infalling gas envelope. This finding fills an important missing piece in our understanding of the early phases of stellar evolution.

    A team led by Yusuke Aso (a graduate student at the University of Tokyo) and Nagayoshi Ohashi (a professor at the Subaru Telescope, National Astronomical Observatory of Japan) observed the baby star named TMC-1A located 450 light years away from us, in the constellation Taurus (the Bull). TMC-1A is a protostar, a star still in the process of forming. Large amounts of gas still surround TMC-1A.

    Stars form in dense gas clouds. Baby stars grow by taking in the surrounding gas, like a fetus receiving nutrition from the mother’s placenta. In this process, gas cannot flow directly into the star. Instead it first accumulates and forms a disk around the star, and then the disk feeds into the star. However, it is still unknown when in the process of star formation this disk appears and how it evolves. Lack of sensitivity and resolution in radio observations has made it difficult to observe these phenomena.

    “The disks around young stars are the places where planets will be formed,” said Aso, the lead author of the paper that appeared in the Astrophysical Journal. “To understand the formation mechanism of a disk, we need to differentiate the disk from the outer envelope precisely and pinpoint the location of its boundary.”

    Using ALMA, the team directly observed the boundary between the inner rotating disk and the outer infalling envelope with high accuracy for the first time. Since gas from the outer envelope is continuously falling into the disk, it had been difficult to identify the transition region in previous studies. In particular, the tenuous but high speed gas in rotating disks is not easy to see. But ALMA has enough sensitivity to highlight such a component and illustrate the speed and distribution of gas in the disk very precisely. This enabled the team to distinguish the disk from the infalling envelope.

    The team found that the boundary between the disk and envelope is located 90 astronomical units from the central baby star. This distance is three times longer than the orbit of Neptune, the outermost planet in the Solar System. The observed disk obeys Keplerian rotation: the material orbiting closer to the central star revolves faster than material further out.

    The high-sensitivity observations provided other important information about the object. From detailed measurement of the rotation speed, the research team could calculate that the mass of the baby star is 0.68 times the mass of the Sun. The team also determined the gas infall rate to be a millionth of the mass of the Sun per year, with a speed of 1 km per second. Gravity causes gas to fall towards the central baby star, but the measured speed is much less than the free-fall speed. Something must be slowing the gas down. The researchers suspect that a magnetic field around the baby star might be what is slowing the gas.

    “We expect that as the baby star grows, the boundary between the disk and the infall region moves outward,” said Aso. “We are sure that future ALMA observations will reveal such evolution.”

    These observational results were published as Aso et al. ALMA Observations of the Transition from Infall Motion to Keplerian Rotation around the Late-phase Protostar TMC-1A in the Astrophysical Journal.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
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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 9:30 am on February 13, 2016 Permalink | Reply
    Tags: ALMA, , , HD 142527 binary system, , Planet Formation around Binary Star,   

    From ALMA: “ALMA Unveils Details of Planet Formation around Binary Star” 

    ALMA Array
    ALMA

    13 February 2016
    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

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

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

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

    Tel: +81 422 34 3630

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

    ALMA Planet Formation around Binary Star
    Artist impression of the HD 142527 binary star system based on data from the Atacama Large Millimeter/submillimeter Array (ALMA). The rendition shows a distinctive arc of dust (red) embedded in the protoplanetary disk. The red arc is free of gas, suggesting the carbon monoxide has “frozen out,” forming a layer of frost on the dust grains in that region. Astronomers speculate this frost provides a boost to planet formation. The two dots in the center represent the two stars in the system. Credit: B. Saxton (NRAO/AUI/NSF)

    Using ALMA, astronomers have taken a new, detailed look at the very early stages of planet formation around a binary star. Embedded in the outer reaches of a double star’s protoplanetary disk, the researchers discovered a striking crescent-shape region of dust that is conspicuously devoid of gas. This result, presented at the AAAS meeting in Washington, D.C., provides fresh insights into the planet-forming potential of a binary system.

    Astronomers struggle to understand how planets form in binary star systems. Early models suggested that the gravitational tug-of-war between two stellar bodies would send young planets into eccentric orbits, possibly ejecting them completely from their home system or sending them crashing into their stars. Observational evidence, however, reveals that planets do indeed form and maintain surprisingly stable orbits around double stars.

    To better understand how such systems form and evolve, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) took a new, detailed look at the planet-forming disk around HD 142527, a binary star about 450 light-years from Earth in a cluster of young stars known as the Scorpius-Centaurus Association.

    The HD 142527 system consists of a main star a little more than twice the mass of our Sun and a smaller companion star only about a third the mass of our Sun. They are separated by approximately one billion miles: a little more than the distance from the Sun to Saturn. Previous ALMA studies of this system revealed surprising details about the structure of the system’s inner and outer disks.

    “This binary system has long been known to harbor a planet-forming corona of dust and gas,” said Andrea Isella, an astronomer at Rice University in Houston, Texas. “The new ALMA images reveal previously unseen details about the physical processes that regulate the formation of planets around this and perhaps many other binary systems.”

    ALMA composite  HD 142527 binary star system
    A composite image of the HD 142527 binary star system from data captured by the Atacama Large Millimeter/submillimeter Array shows a distinctive arc of dust (red) and a ring of carbon monoxide (blue and green). The red arc is free of gas, suggesting the carbon monoxide has “frozen out,” forming a layer of frost on the dust grains in that region. Astronomers speculate this frost provides a boost to planet formation. The two dots in the center represent the two stars in the system. Credit: Andrea Isella/Rice University; B. Saxton (NRAO/AUI/NSF); ALMA (NRAO/ESO/NAOJ)

    Planets form out of the expansive disks of dust and gas that surround young stars. Small dust grains and pockets of gas eventually come together under gravity, forming larger and larger agglomerations and eventually asteroids and planets. The fine points of this process are not well understood, however. By studying a wide range of protoplanetary disks with ALMA, astronomers hope to better understand the conditions that set the stage for planet formation across the Universe.

    ALMA’s new, high-resolution images of HD 142527 show a broad elliptical ring around the double star. The disk begins incredibly far from the central star — about 50 times the Sun-Earth distance. Most of it consists of gases, including two forms of carbon monoxide (13CO and C180), but there is a noticeable dearth of gases within a huge arc of dust that extends nearly a third of the way around the star system.

    This crescent-shaped dust cloud may be the result of gravitational forces unique to binary stars and may also be the key to the formation of planets, Isella speculates. Its lack of free-floating gases is likely the result of them freezing out and forming a thin layer of ice on the dust grains.

    “The temperature is so low that the gas turns into ice and sticks to the grains,” Isella said. “This process is thought to increase the capacity for dust grains to stick together, making it a strong catalyst for the formation of planetesimals, and, down the line, of planets.”

    “We’ve been studying protoplanetary disks for at least 20 years,” Isella said. “There are between a few hundred and a few thousands we can look at again with ALMA to find new and surprising details. That’s the beauty of ALMA. Every time you get new data, it’s like opening a present. You don’t know what’s inside.”

    HD 142527 will be the subject of an upcoming paper led by Rice postdoctoral fellow Yann Boehler, who is working in Isella’s group.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
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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 9:50 am on February 13, 2016 Permalink | Reply

      I have requested the full science team from the contacts listed in the article. If I get the listing, the post will be revised to include it.

      Like

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