From ALMA: “ALMA Explores the Hubble Ultra Deep Field”

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

22 September 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

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

James Dunlop
University of Edinburgh
Edinburgh, United Kingdom
Email: jsd@roe.ac.uk

Fabian Walter
Max-Planck Institut für Astronomie
Heidelberg, Germany
Email: walter@mpia.de

Manuel Aravena
Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales
Santiago, Chile
Email: manuel.aravenaa@mail.udp.cl

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

This image combines a background picture taken by the NASA/ESA Hubble Space Telescope (blue/green) with a new very deep ALMA view of this field (orange, marked with circles). All the objects that ALMA sees appear to be massive star-forming galaxies. This image is based on the ALMA survey by J. Dunlop and colleagues, covering the full HUDF area. Credit: ALMA (ESO/NAOJ/NRAO)/NASA/ESA/J. Dunlop et al. and S. Beckwith (STScI) and the HUDF Team.

These cutout images are from a combination of a background picture taken by the NASA/ESA Hubble Space Telescope (blue/green) with a new very deep ALMA view of the field (orange, marked with circles). All the objects that ALMA sees appear to be massive star-forming galaxies.
This image is based on the ALMA survey by J. Dunlop and colleagues, covering the full HUDF area. Credit:ALMA (ESO/NAOJ/NRAO)/NASA/ESA/J. Dunlop et al. and S. Beckwith (STScI) and the HUDF Team.

Animated GIF showing a trove of galaxies, rich in dust and cold gas (indicating star-forming potential) that was imaged by ALMA (orange) in the Hubble Ultra Deep Field. Credit: B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble

International teams of astronomers have used the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the distant corner of the Universe first revealed in the iconic images of the Hubble Ultra Deep Field (HUDF). These new ALMA observations are significantly deeper and sharper than previous surveys at millimetre wavelengths. They clearly show how the rate of star formation in young galaxies is closely related to their total mass in stars. They also trace the previously unknown abundance of star-forming gas at different points in time, providing new insights into the “Golden Age” of galaxy formation approximately 10 billion years ago.

The new ALMA results will be published in a series of papers appearing in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society. These results are also among those being presented this week at the Half a Decade of ALMA conference in Palm Springs, California, USA.

In 2004 the Hubble Ultra Deep Field images — pioneering deep-field observations with the NASA/ESA Hubble Space Telescope — were published. These spectacular pictures probed more deeply than ever before and revealed a menagerie of galaxies stretching back to less than a billion years after the Big Bang. The area was observed several times by Hubble and many other telescopes, resulting in the deepest view of the Universe to date.

Astronomers using ALMA have now surveyed this seemingly unremarkable, but heavily studied, window into the distant Universe for the first time both deeply and sharply in the millimetre range of wavelengths [1]. This allows them to see the faint glow from gas clouds and also the emission from warm dust in galaxies in the early Universe.

ALMA has observed the HUDF for a total of around 50 hours up to now. This is the largest amount of ALMA observing time spent on one area of the sky so far.

One team led by Jim Dunlop (University of Edinburgh, United Kingdom) used ALMA to obtain the first deep, homogeneous ALMA image of a region as large as the HUDF. This data allowed them to clearly match up the galaxies that they detected with objects already seen with Hubble and other facilities.

This study showed clearly for the first time that the stellar mass of a galaxy is the best predictor of star formation rate in the high redshift Universe. They detected essentially all of the high-mass galaxies [2] and virtually nothing else.

Jim Dunlop, lead author on the deep imaging paper sums up its importance: “This is a breakthrough result. For the first time we are properly connecting the visible and ultraviolet light view of the distant Universe from Hubble and far-infrared/millimetre views of the Universe from ALMA.”

The second team, led by Manuel Aravena of the Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile, and Fabian Walter of the Max Planck Institute for Astronomy in Heidelberg, Germany, conducted a deeper search across about one sixth of the total HUDF [3].

“We conducted the first fully blind, three-dimensional search for cool gas in the early Universe,” said Chris Carilli, an astronomer with the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, USA and member of the research team. “Through this, we discovered a population of galaxies that is not clearly evident in any other deep surveys of the sky.” [4]

Some of the new ALMA observations were specifically tailored to detect galaxies that are rich in carbon monoxide, indicating regions primed for star formation. Even though these molecular gas reservoirs give rise to the star formation activity in galaxies, they are often very hard to see with Hubble. ALMA can therefore reveal the “missing half” of the galaxy formation and evolution process.

“The new ALMA results imply a rapidly rising gas content in galaxies as we look back further in time,” adds lead author of two of the papers, Manuel Aravena (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile). “This increasing gas content is likely the root cause for the remarkable increase in star formation rates during the peak epoch of galaxy formation, some 10 billion years ago.”

The results presented today are just the start of a series of future observations to probe the distant Universe with ALMA. For example, a planned 150-hour observing campaign of the HUDF will further illuminate the star-forming potential history of the Universe.

“By supplementing our understanding of this missing star-forming material, the forthcoming ALMA Large Program will complete our view of the galaxies in the iconic Hubble Ultra Deep Field,” concludes Fabian Walter.
Notes

[1] Astronomers specifically selected the area of study in the HUDF, a region of space in the faint southern constellation of Fornax (The Furnace), so ground-based telescopes in the southern hemisphere, like ALMA, could probe the region, expanding our knowledge about the very distant Universe.

Probing the deep, but optically invisible, Universe was one of the primary science goals for ALMA.

[2] In this context “high mass” means galaxies with stellar masses greater than 20 billion times that of the Sun ( 2 × 1010 solar masses). For comparison, the Milky Way is a large galaxy and has a mass of around 100 billion solar masses.

[3] This region of sky is about seven hundred times smaller than the area of the disc of the full Moon as seen from Earth. One of the most startling aspects of the HUDF was the vast number of galaxies found in such a tiny fraction of the sky.

[4] ALMA’s ability to see a completely different portion of the electromagnetic spectrum from Hubble allows astronomers to study a different class of astronomical objects, such as massive star-forming clouds, as well as objects that are otherwise too faint to observe in visible light, but visible at millimetre wavelengths.

The search is referred to as “blind” as it was not focussed on any particular object.

The new ALMA observations of the HUDF include two distinct, yet complementary types of data: continuum observations, which reveal dust emission and star formation, and a spectral emission line survey, which looks at the cold molecular gas fueling star formation. The second survey is particularly valuable because it includes information about the degree to which light from distant objects has been redshifted by the expansion of the Universe. Greater redshift means that an object is further away and seen farther back in time. This allows astronomers to create a three-dimensional map of star-forming gas as it evolves over cosmic time.
More information

This research was presented in papers titled:

“A deep ALMA image of the Hubble Ultra Deep Field”, by J. Dunlop et al., to appear in the Monthly Notices of the Royal Astronomical Society.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for the [CII] Line and Dust Emission in 6 < z < 8 Galaxies”, by M. Aravena et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-Redshift Galaxies”, by R. Decarli et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Luminosity Functions and the Evolution of the Cosmic Density of Molecular Gas”, by R. Decarli et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2-mm Extragalactic Background, and Properties of the Faintest Dusty Star Forming Galaxies”, by M. Aravena et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description”, by F. Walter et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: the Infrared excess of UV-selected z= 2-10 Galaxies as a Function of UV-continuum Slope and Stellar Mass”, by R. Bouwens et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Implication for spectral line intensity mapping at millimeter wavelengths and CMB spectral distortions”, by C. L. Carilli et al. to appear in the Astrophysical Journal.

The teams are composed of:

M. Aravena (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile), R. Decarli (Max-Planck Institut für Astronomie, Heidelberg, Germany), F. Walter (Max-Planck Institut für Astronomie, Heidelberg, Germany; Astronomy Department, California Institute of Technology, USA; NRAO, Pete V. Domenici Array Science Center, USA), R. Bouwens (Leiden Observatory, Leiden, The Netherlands; UCO/Lick Observatory, Santa Cruz, USA), P.A. Oesch (Astronomy Department, Yale University, New Haven, USA), C.L. Carilli (Leiden Observatory, Leiden, The Netherlands; Astrophysics Group, Cavendish Laboratory, Cambridge, UK), F.E. Bauer (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Institute of Astrophysics, Chile; Space Science Institute, Boulder, USA), E. Da Cunha (Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Australia), E. Daddi (Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, Orme des Merisiers, France), J. Gónzalez-López (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile), R.J. Ivison (European Southern Observatory, Garching bei München, Germany; Institute for Astronomy, University of Edinburgh, Edinburgh, UK), D.A. Riechers (Cornell University, 220 Space Sciences Building, Ithaca, USA), I. Smail (Institute for Computational Cosmology, Durham University, Durham, UK), A.M. Swinbank (Institute for Computational Cosmology, Durham University, Durham, UK), A. Weiss (Max-Planck-Institut für Radioastronomie, Bonn, Germany), T. Anguita (Departamento de Ciencias Físicas, Universidad Andrés Bello, Santiago, Chile; Millennium Institute of Astrophysics, Chile), R. Bacon (Université Lyon 1, Saint Genis Laval, France), E. Bell (Department of Astronomy, University of Michigan, USA), F. Bertoldi (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), P. Cortes (Joint ALMA Observatory – ESO, Santiago, Chile; NRAO, Pete V. Domenici Array Science Center, USA), P. Cox (Joint ALMA Observatory – ESO, Santiago, Chile), J. Hodge (Leiden Observatory, Leiden, The Netherlands), E. Ibar (Instituto de Física y Astronomía, Universidad de Valparaíso, Valparaiso, Chile), H. Inami (Université Lyon 1, Saint Genis Laval, France), L. Infante (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile), A. Karim (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), B. Magnelli (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), K. Ota (Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK; Cavendish Laboratory, University of Cambridge, UK), G. Popping (European Southern Observatory, Garching bei München, Germany), P. van der Werf (Leiden Observatory, Leiden, The Netherlands), J. Wagg (SKA Organization, Cheshire, UK), Y. Fudamoto (European Southern Observatory, Garching bei München, Germany; Universität-Sternwarte München, München, Germany), D. Elbaz (Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, France), S. Chapman (Dalhousie University, Halifax, Nova Scotia, Canada), L.Colina (ASTRO-UAM, UAM, Unidad Asociada CSIC, Spain), H.W. Rix (Max-Planck Institut für Astronomie, Heidelberg, Germany), Mark Sargent (Astronomy Centre, University of Sussex, Brighton, UK), Arjen van der Wel (Max-Planck Institut für Astronomie, Heidelberg, Germany)

K. Sheth (NASA Headquarters, Washington DC, USA), Roberto Neri (IRAM, Saint-Martin d’Hères, France), O. Le Fèvre (Aix Marseille Université, Laboratoire d’Astrophysique de Marseille, Marseille, France), M. Dickinson (Steward Observatory, University of Arizona, USA), R. Assef (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile), I. Labbé (Leiden Observatory, Leiden University, Netherlands), S. Wilkins (Astronomy Centre, University of Sussex, Brighton, UK), J.S. Dunlop (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), R.J. McLure (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), A.D. Biggs (ESO, Garching, Germany), J.E. Geach (University of Hertfordshire, Hatfield, United Kingdom), M.J. Michałowski (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), W. Rujopakarn (Chulalongkorn University, Bangkok, Thailand), E. van Kampen (ESO, Garching, Germany), A. Kirkpatrick (University of Massachusetts, Amherst, Massachusetts, USA), A. Pope (University of Massachusetts, Amherst, Massachusetts, USA), D. Scott (University of British Columbia, Vancouver, British Columbia, Canada), T.A. Targett (Sonoma State University, Rohnert Park, California, USA), I. Aretxaga (Instituto Nacional de Astrofísica, Optica y Electronica, Mexico), J.E. Austermann (NIST Quantum Devices Group, Boulder, Colorado, USA), P.N. Best (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), V.A. Bruce (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), E.L. Chapin (Herzberg Astronomy and Astrophysics, National Research Council Canada, Victoria, Canada), S. Charlot (Sorbonne Universités, UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, Paris, France), M. Cirasuolo (ESO, Garching, Germany), K.E.K. Coppin (University of Hertfordshire, College Lane, Hatfield, United Kingdom), R.S. Ellis (ESO, Garching, Germany), S.L. Finkelstein (The University of Texas at Austin, Austin, Texas, USA), C.C. Hayward (California Institute of Technology, Pasadena, California, USA), D.H. Hughes (Instituto Nacional de Astrofísica, Optica y Electronica, Mexico), S. Khochfar (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), M.P. Koprowski (University of Hertfordshire, College Lane, Hatfield, United Kingdom), D. Narayanan (Haverford College, Haverford, Pennsylvania, USA), C. Papovich (Texas A & M University, College Station, Texas, USA), J.A. Peacock (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), B. Robertson (University of California, Santa Cruz, Santa Cruz, California, USA), T. Vernstrom (Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, Canada), G.W. Wilson (University of Massachusetts, Amherst, Massachusetts, USA) and M. Yun (University of Massachusetts, Amherst, Massachusetts, USA).

Links

Research paper 1 (Dunlop, J. S. et al.)
Research paper 2 (Aravena, M. et al.)
Research paper 3 (Decarli, R. et al.)
Research paper 4 (Decarli, R. et al.)
Research paper 5 (Aravena, M. et al.)
Research paper 6 (Walter, F. et al.)
Research paper 7 (Bouwens, R. et al.)
Research paper 8 (Carilli, C. L. et al.)
NRAO press release
Max Planck Institute for Astronomy press release (English | German)
Photos of ALMA

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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

From ALMA: “ALMA Uncovers Secrets of Giant Space Blob”

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

21 September 2016
Jim Geach
Centre for Astrophysics Research, University of Hertfordshire
Hatfield, UK
Email: j.geach@herts.ac.uk

Matthew Hayes
Stockholm University
Stockholm, Sweden
Tel: +46 (0)8 5537 8521
Email: matthew@astro.su.se

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

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

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

An international team using ALMA, along with ESO’s Very Large Telescope and other telescopes, has discovered the true nature of a rare object in the distant Universe called a Lyman-alpha Blob. Up to now astronomers did not understand what made these huge clouds of gas shine so brightly, but ALMA has now seen two galaxies at the heart of one of these objects and they are undergoing a frenzy of star formation that is lighting up their surroundings. These large galaxies are in turn at the centre of a swarm of smaller ones in what appears to be an early phase in the formation of a massive cluster of galaxies. The two ALMA sources are expected to evolve into a single giant elliptical galaxy.

This diagram explains how a Lyman-alpha Blob, one of the largest and brightest objects in the Universe, shines. Credit: ESO/J. Geach

Lyman-alpha Blobs (LABs) are gigantic clouds of hydrogen gas that can span hundreds of thousands of light-years and are found at very large cosmic distances. The name reflects the characteristic wavelength of ultraviolet light that they emit, known as Lyman-alpha radiation [1]. Since their discovery, the processes that give rise to LABs have been an astronomical puzzle. But new observations with ALMA may now have now cleared up the mystery.

One of the largest Lyman-alpha Blobs known, and the most thoroughly studied, is SSA22-Lyman-alpha blob 1, or LAB-1. Embedded in the core of a huge cluster of galaxies in the early stages of formation, it was the very first such object to be discovered — in 2000 — and is located so far away that its light has taken about 11.5 billion years to reach us.

A team of astronomers, led by Jim Geach, from the Centre for Astrophysics Research of the University of Hertfordshire, UK, has now used the Atacama Large Millimeter/Submillimeter Array’s (ALMA) unparallelled ability to observe light from cool dust clouds in distant galaxies to peer deeply into LAB-1. This allowed them to pinpoint and resolve several sources of submillimetre emission [2].

They then combined the ALMA images with observations from the Multi Unit Spectroscopic Explorer (MUSE) instrument mounted on ESO’s Very Large Telescope (VLT), which map the Lyman-alpha light. This showed that the ALMA sources are located in the very heart of the Lyman-alpha Blob, where they are forming stars at a rate over 100 times that of the Milky Way.

ESO/VLT at Cerro Paranal, Chile

ESO MUSE

Deep imaging with the NASA/ESA Hubble Space Telescope and spectroscopy at the W. M. Keck Observatory [3] showed in addition that the ALMA sources are surrounded by numerous faint companion galaxies that could be bombarding the central ALMA sources with material, helping to drive their high star formation rates.

NASA/ESA Hubble Telescope

NASA/ESA Hubble STIS

Keck Observatory, Mauna Kea, Hawaii, USA

Keck/MOSFIRE on Keck 1, Mauna Kea, Hawaii, USA

The team then turned to a sophisticated simulation of galaxy formation to demonstrate that the giant glowing cloud of Lyman-alpha emission can be explained if ultraviolet light produced by star formation in the ALMA sources scatters off the surrounding hydrogen gas. This would give rise to the Lyman-alpha Blob we see.

Jim Geach, lead author of the new study, explains: “Think of a streetlight on a foggy night — you see the diffuse glow because light is scattering off the tiny water droplets. A similar thing is happening here, except the streetlight is an intensely star-forming galaxy and the fog is a huge cloud of intergalactic gas. The galaxies are illuminating their surroundings.”

Understanding how galaxies form and evolve is a massive challenge. Astronomers think Lyman-alpha Blobs are important because they seem to be the places where the most massive galaxies in the Universe form. In particular, the extended Lyman-alpha glow provides information on what is happening in the primordial gas clouds surrounding young galaxies, a region that is very difficult to study, but critical to understand.

Jim Geach concludes, “What’s exciting about these blobs is that we are getting a rare glimpse of what’s happening around these young, growing galaxies. For a long time the origin of the extended Lyman-alpha light has been controversial. But with the combination of new observations and cutting-edge simulations, we think we have solved a 15-year-old mystery: Lyman-alpha Blob-1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster. We are seeing a snapshot of the assembly of that galaxy 11.5 billion years ago.”

Additional images:

Giant space blob glows from within

This image shows one of the largest known single objects in the Universe, the Lyman-alpha blob LAB-1. This picture is a composite of two different images taken with the FORS instrument on the Very Large Telescope (VLT) — a wider image showing the surrounding galaxies and a much deeper observation of the blob itself at the centre made to detect its polarisation. The intense Lyman-alpha ultraviolet radiation from the blob appears green after it has been stretched by the expansion of the Universe during its long journey to Earth. These new observations show for the first time that the light from this object is polarised. This means that the giant “blob” must be powered by galaxies embedded within the cloud. Credit: ESO/M. Hayes

ESO/FORS1

Closing in on a giant space blob

This sequence of images closes in on one of the largest known single objects in the Universe, the Lyman-alpha blob LAB-1. Observations with the ESO VLT show for the first time that this giant “blob” must be powered by galaxies embedded within the cloud. The image on the left shows a wide view of the constellation of Aquarius. The two images at the upper right were created from photographs taken through blue and red filters and forming part of the Digitized Sky Survey 2. The two images at the lower right were taken using the FORS camera on the VLT.
Credit: ESO/A. Fujii/M. Hayes and Digitized Sky Survey 2

Wide-field view of the sky around a giant space blob

This visible-light wide-field image of the region around the giant Lyman-alpha blob LAB1 was created from photographs taken through blue and red filters and forming part of the Digitized Sky Survey 2. The blob itself lies at the centre of the image but, despite being huge and very luminous, it is so distant that it is too faint to be seen clearly on this picture. The field of view is approximately 2.9 degrees across. Credit: ESO and Digitized Sky Survey 2

Notes

[1] The negatively charged electrons that orbit the positively charged nucleus in an atom have quantised energy levels. That is, they can only exist in specific energy states, and they can only transition between them by gaining or losing precise amounts of energy. Lyman-alpha radiation is produced when electrons in hydrogen atoms drop from the second-lowest to the lowest energy level. The precise amount of energy lost is released as light with a particular wavelength, in the ultraviolet part of the spectrum, which astronomers can detect with space telescopes or on Earth in the case of redshifted objects. For LAB-1, at redshift of z~3, the Lyman-alpha light is seen as visible light.

[2] Resolution is the ability to see that objects are separated. At low resolution, several bright sources at a distance would seem like a single glowing spot, and only at closer quarters would each source be distinguishable. ALMA’s high resolution has resolved what previously appeared to be a single blob into two separate sources.

[3] The instruments used were the Space Telescope Imaging Spectograph (STIS) on the NASA/ESA Hubble Space Telescope and the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) mounted on the Keck 1 telescope on Hawaii.
More information

This research was presented in a paper entitled ALMA observations of Lyman-α Blob 1: Halo sub-structure illuminated from within by J. Geach et al., to appear in the Astrophysical Journal.

The team is composed of J. E. Geach (Centre for Astrophysics Research, University of Hertfordshire, Hatfield, UK), D. Narayanan (Department of Physics and Astronomy, Haverford College, Haverford PA, USA; Department of Astronomy, University of Florida, Gainesville FL, USA), Y. Matsuda (National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan; The Graduate University for Advanced Studies, Mitaka, Tokyo, Japan), M. Hayes (Stockholm University, Department of Astronomy and Oskar Klein Centre for Cosmoparticle Physics, Stockholm, Sweden), Ll. Mas-Ribas (Institute of Theoretical Astrophysics, University of Oslo, Oslo, Norway), M. Dijkstra (Institute of Theoretical Astrophysics, University of Oslo, Oslo, Norway), C. C. Steidel (California Institute of Technology, Pasadena CA, USA ), S. C. Chapman (Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Canada ), R. Feldmann (Department of Astronomy, University of California, Berkeley CA, USA ), A. Avison (UK ALMA Regional Centre Node; Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, UK), O. Agertz (Department of Physics, University of Surrey, Guildford, UK), Y. Ao (National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan), M. Birkinshaw (H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK), M. N. Bremer (H.H. Wills Physics Laboratory, University of Bristol, Bristol, UK), D. L. Clements (Astrophysics Group, Imperial College London, Blackett Laboratory, London, UK), H. Dannerbauer (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain; Universidad de La Laguna, Astrofísica, La Laguna, Tenerife, Spain), D. Farrah (Department of Physics, Virginia Tech, Blacksburg VA, USA), C. M. Harrison (Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK), M. Kubo (National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan), M. J. Michałowski (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK), D. Scott (Department of Physics & Astronomy, University of British Columbia, Vancouver, Canada), M. Spaans (Kapteyn Astronomical Institute, University of Groningen, Groningen, Netherlands) , J. Simpson (Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK), A. M. Swinbank (Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, UK ), Y. Taniguchi (The Open University of Japan, Chiba, Japan), E. van Kampen (ESO, Garching, Germany), P. Van Der Werf (Leiden Observatory, Leiden University, Leiden, The Netherlands), A. Verma (Oxford Astrophysics, Department of Physics, University of Oxford, Oxford, UK) and T. Yamada (Astronomical Institute, Tohoku University, Miyagi, Japan).

[This is the ESO release on this work. At this time, ALMA has not released their article. When ALMA releases their article, I may substitute it for this article. But this article makes very clear that this is an ALMA project.]
[I have added from the ALMA release Nicolás Lira T and Charles E. Blue to the contact list above]
[There is no material difference between the ESO and ALMA releases.]

See the full article here .

See the full ALMA release here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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

From ALMA: “Black Hole Hidden Within Its Own Exhaust”

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

15 September 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

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

Artist impression of the heart of galaxy NGC 1068, which harbors an actively feeding supermassive black hole. Arising from the black hole’s outer accretion disk, ALMA discovered clouds of cold molecular gas and dust. This material is being accelerated by magnetic fields in the disk, reaching speeds of about 400 to 800 kilometers per second. This material gets expelled from the disk and goes on to hide the region around the black hole from optical telescopes on Earth. Essentially, the black hole is cloaking itself behind a veil of its own exhaust. Credit: NRAO/AUI/NSF; D. Berry / Skyworks

Supermassive black holes, millions to billions of times the mass of our Sun, are found at the centers of galaxies. Many of these galactic behemoths are hidden within a thick doughnut-shape ring of dust and gas known as a torus. Previous observations suggest these cloaking, tire-like structures are formed from the native material found near the center of a galaxy.

New data from the Atacama Large Millimeter/submillimeter Array (ALMA), however, reveal that the black hole at the center of a galaxy named NGC 1068 is actually the source of its own dusty torus of dust and gas, forged from material flung out of the black hole’s accretion disk.

This newly discovered cosmic fountain of cold gas and dust could reshape our understanding of how black holes impact their host galaxy and potentially the intergalactic medium.

“Think of a black hole as an engine. It’s fueled by material falling in on it from a flattened disk of dust and gas,” said Jack Gallimore, an astronomer at Bucknell University in Lewisburg, Pennsylvania, and lead author on a paper published in Astrophysical Journal Letters. “But like any engine, a black hole can also emit exhaust.” That exhaust, astronomers discovered, is the likely source of the torus of material that effectively obscures the region around the galaxy’s supermassive black hole from optical telescopes.

NGC 1068 (also known as Messier 77) is a barred spiral galaxy approximately 47 million light-years from Earth in the direction of the constellation Cetus (aka th ‘Whale’). At its center is an active galactic nucleus, a supermassive black hole that is being fed by a thin, rotating disk of gas and dust known as an accretion disk. As material in the disk spirals toward the central black hole, it becomes superheated and blazes bright with ultraviolet radiation. The outer reaches of the disk, however, are considerably cooler and glow more appreciably in infrared light and the millimeter-wavelength light that ALMA can detect.

Using ALMA, an international team of astronomers peered deep into this region and discovered a sprinkling of cool clouds of carbon monoxide lifting off the outer portion of the accretion disk. The energy from the hot inner disk partially ionizes these clouds, enabling them to adhere to powerful magnetic field lines that wrap around the disk.

Like water being flung out of a rapidly rotating garden sprinkler, the clouds rising above the accretion disk get accelerated centrifugally along the magnetic field lines to very high speeds — approximately 400 to 800 kilometers per second (nearly 2 million miles per hour). This is up to nearly three times faster than the rotational speed of the outer accretion disk, fast enough to send the clouds hurtling further out into the galaxy.

ALMA image of the central region of galaxy NGC 1068. The torus of material harboring the supermassive black hole is highlighted in the pullout box. This region, which is approximately 40 light-years across, is the result of material flung out of the black hole’s accretion disk. The colors in this image represent the motion of the gas: blue is material moving toward us, red moving away. The areas in green are low velocity and consistent with rotation around a black hole. The white in the central region means the gas is moving both toward and away at very high speed, the conditions illustrated in the artist impression. The outer ring area is unrelated to the black hole and is more tied to the structure of the central 1,000 light-years of the host galaxy. Credit: Gallimore et. al; ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF)

“These clouds are traveling so fast that they reach ‘escape velocity’ and are jettisoned in a cone-like spray from both sides of the disk,” said Gallimore. “With ALMA, we can for the first time see that it is the gas that is thrown out that hides the black hole, not the gas falling in.” This suggests that the general theory of an active black hole is oversimplified, he concludes.

With future ALMA observations, the astronomers hope to work out a fuel budget for this black hole engine: how much mass per year goes into the black hole and how much is ejected as exhaust.

“These are fundamental quantities for understanding black holes that we really don’t have a good handle on at this time,” concludes Gallimore.

Additional information

This research is presented in the paper titled “High-velocity bipolar molecular emission from an AGN torus,” by J. Gallimore et al., published in Astrophysical Journal Letters on 15 September 2016. Preprint: http://arxiv.org/pdf/1608.02210v1.pdf

The team is composed of Jack Gallimore (Bucknell University, Lewisburg, Pennsylvania), Moshe Elitzur (University of California, Berkeley), Roberto Maiolino (University of Cambridge, U.K.), Alessandro Marconi (University of Firenze, Italy), Christopher P. O’Dea (University of Manitoba, Winnipeg, Canada), Dieter Lutz (Max Planck Institute for Extraterrestrial Physics, Garching, Germany), Stefi A. Baum, University of Manitoba, Winnipeg, Canada), Robert Nikutta (Catholic University of Chile, Santiago), C.M.V. Impellizzeri (Joint ALMA Observatory, Santiago, Chile), Richard Davies (Max Planck Institute for Extraterrestrial Physics, Garching, Germany), Amy E. Kimball (National Radio Astronomy Observatory, Socorro, New Mexico), Eleonora Sani (European Southern Observatory, Santiago, Chile).

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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

From ALMA: “ALMA Spots Possible Formation Site of Icy Giant Planet”

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

12 September 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

Astronomers found a sign of a growing planet around TW Hydra, a nearby young star, using the Atacama Large Millimeter/submillimeter Array (ALMA). Based on the distance from the central star and distribution of tiny dust grains, the baby planet is estimated to be an icy giant, similar to Uranus and Neptune in our Solar System. This result is another step for understanding the origins of various types of planets.

A number of extrasolar planets have been found in the past two decades and now researchers have a common view that planets take a wide variety of characteristics. However, it is still unclear how this diversity emerges. Especially, there is still debate about how the icy giant planets, such as Uranus and Neptune, form.

To take a close look at the planet formation site, a research team led by Takashi Tsukagoshi at Ibaraki University, Japan, observed the young star TW Hydrae. This star, estimated to be 10 million years old, is one of the closest young stars to the Earth. Thanks to the proximity and the fact that its axis of rotation points roughly in the Earth’s direction, giving us a face-on-view of the developing planetary system, TW Hydrae is one of the most favorable targets for investigating planet formation.

Past observations have shown that TW Hydrae is surround by a disk of tiny dust particles. This disk is the site of planet formation. Recent ALMA observations revealed multiple gaps in the disk [1]. Some theoretical studies suggest that the gaps are the evidence of planet formation.

Figure 1. ALMA image of the disk around the young star TW Hydrae. Several gaps are clearly depicted. Researchers found that the size of the dust particles in the inner 22 au gap is smaller than the other bright regions and guess that a planet similar to Neptune is located in this gap. Credit: ALMA (ESO/NAOJ/NRAO), Tsukagoshi et al.

The team observed the disk around TW Hydrae with ALMA in two radio frequencies. Since the ratio between the intensities in different radio frequencies depends on the size of the dust grains, researchers can estimate it. This ratio indicates that the smaller, micrometer-sized dusts dominates and larger dusts are missing in the most prominent gap with the radius of 22 au [2].

Why are smaller dust particles selectively located in the gap in the disk? Theoretical studies have predicted that a gap in the disk is created by a massive planet, and that gravitational interaction and friction between gas and dust particles push the larger dust out from the gap, while the smaller particles remain in the gap. The current observation results match the theoretical prediction.

Figure 2. Artist’s impression of the dust disk and a forming planet around TW Hydrae. Credit: NAOJ

Researchers calculated the mass of the unseen planet based on the width and depth of the 22 au gap and found that the planet is a little more massive than Neptune. “Combined with the orbit size and the brightness of TW Hydrae, the planet would be an icy giant planet,” said Tsukagoshi.

Following this result, the team is planning further observations to better understand planet formation. One of their plans is to observe polarization of the radio waves. Recent theoretical studies have shown that the size of dust grains can be estimated more precisely with polarization observations. The other plan is to measure the amount of gas in the disk. Since gas is the major component of the disk, the researchers hope to attain a better estimation of the mass of the forming planet.

Notes

See the press release ALMA’s Best Image of a Protoplanetary Disk issued on March 30, 2016 for more detail. Astronomers observed radio waves from TW Hydrae in only one frequency in the past observations and could not estimate the size of the dust particles.

1 au = 1 astronomical unit. One astronomical unit corresponds to the distance between the Sun and the Earth, about 150 million kilometers.

Additional information

These observation results were accepted for a publication as Tsukagoshi et al. A Gap with a Deficit of Large Grains in the Protoplanetary Disk around TW Hya by the Astrophysical Journal Letters.

The research team members are:

Takashi Tsukagoshi (Ibaraki University), Hideko Nomura (Tokyo Institute of Technology), Takayuki Muto (Kogakuin University), Ryohei Kawabe (National Astronomical Observatory of Japan, National Institutes for National Sciences), Daiki Ishimoto (Tokyo Institute of Technology/Kyoto University), Kazuhiro D. Kanagawa (University of Szczecin), Satoshi Okuzumi (Tokyo Institute of Technology), Shigeru Ida (Tokyo Institute of Technology), Catherine Walsh (Leiden University), T. J. Millar (Queen’s University Belfast).

This research was supported by the Japan Society for the Promotion of Science through Grants-in-Aid for Scientific Research No. 24103504, 23103005, 25400229, 26800106, 15H02074, 16K17661, and Polish National Science Centre MAESTRO grant DEC- 2012/06/A/ST9/00276.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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

From SEEKER: “The Race to See Our Supermassive Black Hole”

SEEKER

May 26, 2016 [Article brought forward by ESO]
No writer credit found

Using the power of interferometry, two astronomical projects are, for the first time, close to directly observing the black hole in the center of the Milky Way.

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

There’s a monster living in the center of the galaxy.

We know the supermassive black hole is there by tracking the motions of stars and gas clouds that orbit an invisible point. That point exerts an overwhelming tidal influence on all objects that get trapped in its gravitational domain and this force can be measured through stellar orbits to calculate its mass.

It certainly isn’t the biggest black hole in the universe, but it isn’t the smallest either, it “weighs in” at an incredible 4 million times the mass of our sun.

But this black hole behemoth, called Sagittarius A*, is over 20,000 light-years from Earth making direct observations, before now, nigh-on impossible. Despite its huge mass, the black hole is minuscule when seen from Earth; a telescope with an unprecedented angular resolution is needed.

Though we already know a lot about Sagittarius A* from indirect observations, seeing is believing and there’s an international race, using the world’s most powerful observatories and sophisticated astronomical techniques, to zoom-in on the Milky Way’s black hole. This won’t only prove it’s really there, but it will reveal a region where space-time is so warped that we will be able to make direct tests of general relativity in the strongest gravity environment known to exist in the universe.

The Event Horizon Telescope and GRAVITY

A huge global effort is currently under way to link a network of global radio telescopes to create a virtual telescope that will span the width of our planet. Using the incredible power of interferometry, astronomers can combine the light from many distant radio antennae and collect it at one point, to mimic one large radio antenna spanning the globe.

Event Horizon Telescope Array

Event Horizon Telescope map

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

Atacama Pathfinder EXperiment (APEX)

Combined Array for Research in Millimeter-wave Astronomy (CARMA)

Atacama Submillimeter Telescope Experiment (ASTE)

Caltech Submillimeter Observatory (CSO)

Institut de Radioastronomie Millimetrique (IRAM) 30m

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

Large Millimeter Telescope Alfonso Serrano

Submillimeter Array Hawaii SAO

Future Array/Telescopes

ESO/NRAO/NAOJ ALMA Array, Chile

Plateau de Bure interferometer

South Pole Telescope SPTPOL

This effort is known as the Event Horizon Telescope (EHT) and it is hoped the project will be able to attain the angular resolution and spatial definition required to soon produce its first radio observations of the bright ring just beyond Sagittarius A*’s event horizon — the point surrounding a black hole where nothing, not even light, can escape.

However, another project has the same goal in mind, but it’s not going to observe in radio wavelengths, it’s going to stare deep into the galactic core to seek out optical and infrared light coming from Sagittarius A* and it just needs one observatory to make this goal a reality.

The ESO Very Large Telescope located atop Cerro Paranal in Chile. Ian O’Neill

The GRAVITY instrument is currently undergoing commissioning at the ESO’s Very Large Telescope at Paranal Observatory high in the Atacama Desert in Chile (at an altitude of over 2,600 meters or 8,300 ft) and it will also use the power of interferometry to resolve our supermassive black hole. But rather than connecting global observatories like the EHT, GRAVITY will combine the light of the four 8 meter telescopes of the VLT Interferometer (collectively known as the VLTI) to create a “virtual” telescope measuring the distance between each individual telescope.

ESO GRAVITY insrument

“By doing this you can reach the same resolution and precision that you would get from a telescope that has a size, in this case, of roughly a hundred meters, simply because these eight meter-class telescopes are separated by roughly one hundred meters,” astronomer Oliver Pfuhl, of Max Planck Institute for Extraterrestrial Physics, Germany, told DNews. “If you combine the light from those you reach the same resolution as a virtual telescope of a hundred meters would have.”

Strong Gravity Environment

When GRAVITY is online it will be used to track features just outside Sagittarius A*’s event horizon.

“For about ten years, we’ve known that this black hole is actually not black. Once in awhile it flares, so we see it brightening and darkening,” he said. This flaring is matter falling into the event horizon, generating a powerful flash of energy. The nature of these flares are poorly understood, but the instrument should be able to track this flaring material as it rapidly orbits the event horizon and fades away. These flares will also act as tracers, helping us see the structure of space-time immediately surrounding a black hole for the first time.

One of the four Very Large Telescope domes fires its new four-laser adaptive optics system. GRAVITY will make use of adaptive optics to improve observations of Sagittarius A* by compensating for the effects of atmospheric turbulence. ESO

“Our goal is to measure these motions. We think that what we see as this flaring is actually gas which spirals into the black hole. This brightening and darkening is essentially the gas, when it comes too close to the black hole, the strong tidal forces make it heat up,” said Pfuhl.

“If we can study these motions which happen so close to the black hole, we have a direct probe of the space time close to the black hole. In this way we have a direct test of general relativity in one of the most extreme environments which you can find in the universe.”

While GRAVITY will be able to track these flaring events very close to the black hole, the Event Horizon Telescope will see the shadow, or silhouette, of the dark event horizon surrounded by radio wave emissions. Both projects will be able to measure different components of the region directly surrounding the event horizon, so combined observations in optical and radio wavelengths will complement one other.

It just so happens that the Atacama Large Millimeter/submillimeter Array (ALMA), the largest radio observatory on the planet — also located in the Atacama Desert — will also be added to the EHT.

“The Event Horizon Telescope will combine ALMA with telescopes around the world like Hawaii and other locations, and with that power you can look at really fine details especially in the black hole in the center of our galaxy and perhaps in some really nearby other galaxies that also have black holes in their centers,” ESO astronomer Linda Watson told DNews.

The ALMA antenna in a clustered formation on Chajnantor plateau during the #MeetESO event on May 11, 2016. The extreme location of the observatory can produce unpredictable weather and, as depicted here, a blizzard descended on the plateau cutting the visit short.
Ian O’Neill

ALMA itself is an interferometer combining the collecting power of 66 radio antennae located atop Chajnantor plateau some 5,000 meters (16,400 ft) in altitude. Watson uses ALMA data to study the cold dust in interstellar space, but when added to the EHT, its radio-collecting power will help us understand the dynamics of the environment surrounding Sagittarius A*.

“ALMA’s an interferometer with 66 antennas, (the EHT) will treat ALMA as just one telescope and will combine it with other telescopes around the world to be another interferometer,” she added.

Black Hole Mysteries

Many black holes are thought to possess an accretion disk of swirling gas and dust. ALMA, when combined with the EHT, will be able to measure this disk’s structure, speed and direction of motion. Lacking direct observations, many of these characteristics have only been modeled by computer simulations or inferred from indirect observations. We’re about to enter an era when we can truly get to answer some of the biggest mysteries surrounding black hole dynamics.

“The first thing we want to see is we want to understand how accretion works close to the black hole,” said Pfuhl. “This is also true for the Event Horizon Telescope. Another thing we want to learn is does our black hole have spin? That means, does it rotate?”

Though the EHT and GRAVITY are working at different wavelengths, observing phenomena around Sagittarius A* will reveal different things about the closest supermassive black hole to Earth. By extension it is hoped that we may observe smaller black holes in our galaxy and other supermassive black holes in neighboring galaxies.

Computer simulation of what theoretical physiicists expect to see with the EHT — a round, dark disk surrounded by radio emissions.
Avery E. Broderick/Univ. of Waterloo/Perimeter Institute (screenshot from the Convergence meeting)

But as we patiently wait for the first direct observations of the black hole monster lurking in the center of our galaxy, an event that some scientists say will be as historic as the “Pale Blue Dot” photo of Earth as captured by Voyager 1 in 1990, it’s hard not to wonder which project will get there first.

“I think it’s a very tight race,” said Pfuhl. “Let’s see.”

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

From ALMA: “ALMA Finds Unexpected Trove of Gas Around Larger Stars”

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

25 August 2016
Contacts

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

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

Artist impression of a debris disk surrounding a star in the Scorpius-Centaurus Association. ALMA discovered that — contrary to expectations — the more massive stars in this region retain considerable stores of carbon monoxide gas. This finding could offer new insights into the timeline for giant planet formation around young stars. Credit: NRAO/AUI/NSF; D. Berry / SkyWorks

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) surveyed dozens of young stars – some Sun-like and others nearly double that size – and discovered that the larger variety have surprisingly rich reservoirs of carbon monoxide gas in their debris disks. In contrast, the lower-mass, Sun-like stars have debris disks that are virtually gas-free.

This finding runs counter to astronomer’s expectations, which hold that stronger radiation from larger stars should strip away gas from their debris disks faster than the comparatively mild radiation from smaller stars. It may also offer new insights into the timeline for giant planet formation around young stars.

Debris disks are found around stars that have shed their dusty, gas-filled protoplanetary disks and gone on to form planets, asteroids, comets, and other planetesimals. Around younger stars, however, many of these newly formed objects have yet to settle into stately orbits and routinely collide, producing enough rubble to spawn a “second-generation” disk of debris.

“Previous spectroscopic measurements of debris disks revealed that certain ones had an unexpected chemical signature suggesting they had an overabundance of carbon monoxide gas,” said Jesse Lieman-Sifry, lead author on a paper published in Astrophysical Journal. At the time of the observations, Lieman-Sifry was an undergraduate astronomy major at Wesleyan University in Middletown, Connecticut. “This discovery was puzzling since astronomers believe that this gas should be long gone by the time we see evidence of a debris disk,” he said.

In search of clues as to why certain stars harbor gas-rich disks, Lieman-Sifry and his team surveyed 24 star systems in the Scorpius-Centaurus Association. This loose stellar agglomeration, which lies a few hundred light-years from Earth, contains hundreds of low- and intermediate-mass stars. For reference, astronomers consider our Sun to be a low-mass star.

The astronomers narrowed their search to stars between five and ten million years old — old enough to host full-fledged planetary systems and debris disks — and used ALMA to examine the millimeter-wavelength “glow” from the carbon monoxide in the star’s debris disks.

The team carried out their survey over a total of six nights between December 2013 and December 2014, observing for a mere ten minutes each night. At the time it was conducted, this study constituted the most extensive millimeter-wavelength interferometric survey of stellar debris disks ever achieved.

ALMA image of the debris disk surrounding a star in the Scorpius-Centaurus Association known as HIP 73145. The green region maps the carbon monoxide gas that suffuses the debris disk. The red is the millimeter-wavelength light emitted by the dust surrounding the central star. The star HIP 73145 is estimated to be approximately twice the mass of the Sun. The disk in this system extends well past what would be the orbit of Neptune in our solar system, drawn in for scale. The location of the central star is also highlighted for reference. Credit: J. Lieman-Sifry, et al., ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AIU/NSF)

Armed with an incredibly rich set of observations, the astronomers found the most gas-rich disks ever recorded in a single study. Among their sample of two dozen disks, the researchers spotted three that exhibited strong carbon monoxide emission. Much to their surprise, all three gas-rich disks surrounded stars about twice as massive as the Sun. None of the 16 smaller, Sun-like stars in the sample appeared to have disks with large stores of carbon monoxide. These observations suggest that larger stars are more likely to sport disks with significant gas reservoirs than Sun-like stars.

This finding is counterintuitive, because higher-mass stars flood their planetary systems with energetic ultraviolet radiation that should destroy the carbon monoxide gas lingering in their debris disks. This new research reveals, however, that the larger stars are somehow able to either preserve or replenish their carbon monoxide stockpiles.

“We’re not sure whether these stars are holding onto reservoirs of gas much longer than expected, or whether there’s a sort of ‘last gasp’ of second-generation gas produced by collisions of comets or evaporation from the icy mantles of dust grains,” said Meredith Hughes, an astronomer at Wesleyan University and coauthor of the study.

The existence of this gas may have important implications for planet formation, says Hughes. Carbon monoxide is a major constituent of the atmospheres of giant planets. Its presence in debris disks could mean that other gases, including hydrogen, are present, but perhaps in much lower concentrations. If certain debris disks are able to hold onto appreciable amounts of gas, it might push back the expected deadline for giant planet formation around young stars, the astronomers speculate.

ALMA image of the debris disk surrounding a star in the Scorpius-Centaurus Association known as HIP 73145. The green region maps the carbon monoxide gas that suffuses the debris disk. The red is the millimeter-wavelength light emitted by the dust surrounding the central star. The star HIP 73145 is estimated to be approximately twice the mass of the Sun. The disk in this system extends well past what would be the orbit of Neptune in our solar system. Credit: J. Lieman-Sifry, et al., ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AIU/NSF)

“Future high-resolution observations of these gas-rich systems may allow astronomers to infer the location of the gas within the disk, which may shed light on the origin of the gas,” says Antonio Hales, an astronomer with the Joint ALMA Observatory in Santiago, Chile, and the National Radio Astronomy Observatory in Charlottesville, Virginia, and coauthor on the study. “For instance, if the gas was produced by planetesimal collisions, it should be more highly concentrated in regions of the disk where those impacts occurred. ALMA is the only instrument capable of making these kind of high-resolution images.”

According to Lieman-Sifry, these dusty disks are just as diverse as the planetary systems they accompany. The discovery that the debris disks around some larger stars retain carbon monoxide longer than their Sun-like counterparts may provide insights into the role this gas plays in the development of planetary systems.

Four out of 24 debris disks observed by ALMA in the Scorpius-Centaurus Association. Researchers were surprised to discover that the larger, more energetic stars retained much more gas in their debris disks than smaller, Sun-like stars. Credit: Lieman-Sifry et al. ALMA (ESO/NAOJ/NRAO); B. Saxton, NRAO/AUI/NSF

Additional information

This research is presented in the paper titled “Debris disks in the Scorpius-Centaurus OB association resolved by ALMA,” by J. Lieman-Sifry et al., published in Astrophysical Journal on 23 August 2016. [Preprint: http://arxiv.org/abs/1606.07068.

The team is composed of Jesse Lieman-Sifry (Wesleyan Univ., Middletown, Connecticut), A. Meredith Hughes (Wesleyan Univ., Middletown, Connecticut), John M. Carpenter (California Institute of Technology, Pasadena), Uma Gorti (SETI Institute, Mountain View, California), Antonio Hales (Joint ALMA Observatory, Santiago, Chile, and National Radio Astronomy Observatory, Charlottesville, Virginia), and Kevin M. Flaherty (Wesleyan Univ., Middletown, Connecticut).

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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

From ALMA: “ALMA Achieved Highest Polarimetric Sensitivity”

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

Monday, 18 July 2016 [Just found this at ALMA’s website. Never saw it in social media.]
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
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3C 286 observed with ALMA. Contours shows the intensity of radio waves and purple bars shows the polarization direction. The central part of the quasar is located in the center of the image, and a part of the jet ejected by the quasar is seen on the right. Credit: ALMA (ESO/NAOJ/NRAO), Nagai et al.

Researchers have confirmed ALMA’s unprecedented capability for polarimetry in millimeter/submillimeter wavebands. Polarimetry is an important method to investigate magnetic fields in the Universe and astronomers are eager to use ALMA for unveiling magnetic mysteries, such as the launching mechanism of high energy jets from supermassive black holes.

The magnetic field is ubiquitous and plays considerable roles in the Universe. We can find the directions by using a compass thanks to Earth’s magnetic field. Sunspots and solar flares are driven by magnetic fields in the Sun. Magnetic fields are also important in various occasions including formation of stars and planets, and exotic events around black holes. In spite of its significance, measurement of magnetic fields is difficult. Polarimetry is one of the handful methods to investigate magnetic fields in the Universe.

ALMA is designed to perform sensitive polarimetry observations. To verify its capability, astronomers observe well-known objects and compare the results with those of existing telescopes. ALMA started science observations in 2011, but in parallel, science verification activities for advanced observation methods have been carried out.

ALMA observed the bright source 3C 286 for the verifications of polarimetry observations. The source, located 7.3 billion light years away from us, is a quasar, emitting very strong radio waves. Many researchers assume that a supermassive black hole is located in the center of a quasar and intense magnetic fields are responsible for ejecting powerful jets. ALMA pointed to the root of the jet from 3C 286 to measure the intensity and the direction of the polarized wave. The result reveal details not seen before and clearly show that the magnetic field is stronger and more ordered towards the inner region of the jet that emerges from the quasar. This helps researchers to understand the magnetic field structure in the very heart of the quasar, furnishing vital clues about the physical processes that give rise to the radio emission.

“This observation has certainly verified the high capability of the polarimetry observation with ALMA,” said Hiroshi Nagai at the National Astronomical Observatory of Japan and the leader of the verification team. “This is an important milestone for the ALMA project.”

In general, the polarized component is as weak as a few percent of the total radio flux from an object. High sensitivity is essential for the precise polarimetry, and ALMA is suitable for it. The science verification activity includes the establishment of the proper calibration and many test observations have been performed to ensure the high precision. Such behind-the-scenes efforts provide a firm platform for advanced observations with ALMA.

Additional information

These observation results were published by Nagai et al. as “ALMA Science Verification Data: Millimeter Continuum Polarimetry of the Bright Radio Quasar 3C 286” in the Astrophysical Journal issued on 20 June 2016.

The science verification activities for polarimetry is introduced in an article Polarization observations with ALMA in the serial column “¡Bienvenido a ALMA!”.

The first scientific results containing ALMA full polarization data were published by the Astrophysical Journal Letters on June 30, 2016, as Interferometric Mapping Of Magnetic Fields: The Alma View Of The Massive Star-Forming Clump W43-MM1 by Cortés et al.

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.

From U Manchester: “Astronomers Uncover Hidden Stellar Birthplace”

University of Manchester

26 July, 2016
Joe Paxton

No image caption. No image credit.

A team of astronomers from the University of Manchester, the Max Planck Institute for Radio Astronomy and the University of Bonn have uncovered a hidden stellar birthplace in a nearby spiral galaxy, using a telescope in Chile. The results show that the speed of star formation in the centre of the galaxy – and other galaxies like it – may be much higher than previously thought.

The team penetrated the thick dust around the centre of galaxy NGC 4945 using the Atacama Large Millimeter Array (ALMA), a single telescope made up of 66 high precision antennas located 5000 metres above sea level in northern Chile.

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

Astronomers typically look for ultraviolet light or infrared emissions from the brightest, hottest, and bluest stars. The places where stars form are often surrounded by interstellar dust that absorbs the ultraviolet and visible light from the hot blue stars, making it difficult to see where stars are forming. However, the interstellar dust gets warmer when it absorbs light and produces infrared radiation.

NGC 4945 is unusual because the interstellar dust is so dense that it even absorbs the infrared light that it produces, meaning that astronomers find it hard to know what is happening in the centre of the galaxy. However, ALMA is able to see through even the thickest interstellar dust.

“When we looked at the galaxy with ALMA, its centre was ten times brighter than we would have anticipated based on the mid-infrared image. It was so bright that I asked one of my collaborators to check my calculations just to make sure that I hadn’t made an error.”
Dr. George J. Bendo

“While it looks very dusty and very bright in the infrared compared to the Milky Way or other nearby spiral galaxies, it is very similar to other infrared-bright starburst galaxies that are more common in the more distant universe. If other astronomers are trying to look at star formation using infrared light, they might be missing a lot of what’s happening if the star forming regions are as obscured as in NGC 4945.”

Fellow collaborator Professor Gary Fuller, also from the University of Manchester, added: “These results demonstrate the remarkable power of ALMA to study star formation which would otherwise be hidden.”

See the full article here .

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The University of Manchester (UoM) is a public research university in the city of Manchester, England, formed in 2004 by the merger of the University of Manchester Institute of Science and Technology (renamed in 1966, est. 1956 as Manchester College of Science and Technology) which had its ultimate origins in the Mechanics’ Institute established in the city in 1824 and the Victoria University of Manchester founded by charter in 1904 after the dissolution of the federal Victoria University (which also had members in Leeds and Liverpool), but originating in Owens College, founded in Manchester in 1851. The University of Manchester is regarded as a red brick university, and was a product of the civic university movement of the late 19th century. It formed a constituent part of the federal Victoria University between 1880, when it received its royal charter, and 1903–1904, when it was dissolved.

The University of Manchester is ranked 33rd in the world by QS World University Rankings 2015-16. In the 2015 Academic Ranking of World Universities, Manchester is ranked 41st in the world and 5th in the UK. In an employability ranking published by Emerging in 2015, where CEOs and chairmen were asked to select the top universities which they recruited from, Manchester placed 24th in the world and 5th nationally. The Global Employability University Ranking conducted by THE places Manchester at 27th world-wide and 10th in Europe, ahead of academic powerhouses such as Cornell, UPenn and LSE. It is ranked joint 56th in the world and 18th in Europe in the 2015-16 Times Higher Education World University Rankings. In the 2014 Research Excellence Framework, Manchester came fifth in terms of research power and seventeenth for grade point average quality when including specialist institutions. More students try to gain entry to the University of Manchester than to any other university in the country, with more than 55,000 applications for undergraduate courses in 2014 resulting in 6.5 applicants for every place available. According to the 2015 High Fliers Report, Manchester is the most targeted university by the largest number of leading graduate employers in the UK.

The university owns and operates major cultural assets such as the Manchester Museum, Whitworth Art Gallery, John Rylands Library and Jodrell Bank Observatory which includes the Grade I listed Lovell Telescope.

From CfA: “The Role of Magnetic Fields in Star-Formation”

Smithsonian Astrophysical Observatory

July 1, 2016
No writer credit

A false-color far-infrared image of the star forming region W43; the contours are for molecular gas density. The subregion MM1 located just left of center in not conspicuous in the image but is the site of massive star formation and fragmentation. A new study has mapped the magnetic fields in this region, and found they are not strong enough to prevent further gravitational collapse. ESA/Herschel and L.Q. Nguyen et al.

The star forming molecular clump W43-MM1 is very massive and dense, containing about 2100 solar-masses of material in a region only one-third of a light-year across (for comparison, the nearest star to the Sun is a bit over four light-years away). Previous observations of this clump found evidence for infalling motions (signaling that material is still accumulating onto a new star) and weak magnetic fields. These fields are detected by looking for polarized light, which is produced when radiation scatters off of elongated dust grains aligned by magnetic fields. The Submillimeter Array recently probed this source with high spatial resolutions and found evidence for even stronger magnetic fields in places. One of the outstanding issues in star formation is the extent to which magnetic fields inhibit the collapse of material onto stars, and this source seems to offer a particularly useful example.

CfA astronomers Josep Girart and TK Sridharan and their colleagues have used the ALMA submillimeter facility to obtain images with spatial scales as small as 0.03 light-years. Their detailed polarization maps show that the magnetic field is well ordered all across the clump, which itself is actually fifteen smaller fragments, one of which (at 312 solar-masses) appears to be the most massive fragment known.

The scientists analyze the magnetic field strengths and show that, even in the least massive fragment the field is not strong enough to inhibit gravitational collapse. In fact, they find indications that gravity, as it pulls material inward, drags the magnetic field lines along. They are, however, unable to rule out possible further fragmentation. The research is the most precise study of magnetic fields in star forming massive clumps yet undertaken, and provides a new reference point for theoretical models.

Reference(s):

Interferometric Mapping of Magnetic Fields: The ALMA View of the Massive Star-forming Clump W43-MM1, Paulo C. Cortes, Josep M. Girart, Charles L. H. Hull, Tirupati K. Sridharan, Fabien Louvet, Richard Plambeck, Zhi-Yun Li, Richard M. Crutcher, and Shih-Ping Lai, ApJ 825, L15, 2016.

See the full article here .

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About CfA

The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy. The long relationship between the two organizations, which began when the SAO moved its headquarters to Cambridge in 1955, was formalized by the establishment of a joint center in 1973. The CfA’s history of accomplishments in astronomy and astrophysics is reflected in a wide range of awards and prizes received by individual CfA scientists.

Today, some 300 Smithsonian and Harvard scientists cooperate in broad programs of astrophysical research supported by Federal appropriations and University funds as well as contracts and grants from government agencies. These scientific investigations, touching on almost all major topics in astronomy, are organized into the following divisions, scientific departments and service groups.

From ALMA: “ALMA Observes First Protoplanetary Water Snow Line Thanks to Stellar Outburst”

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

13 July 2016
Lucas Cieza
Universidad Diego Portales
Santiago, Chile
Tel: +56 22 676 8154
Cell: +56 95 000 6541
Email: lucas.cieza@mail.udp.cl

Nicolás Lira T.
Education and Public Outreach Coordinator
Joint ALMA Observatory
Santiago, Chile
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Email: nicolas.lira@alma.cl

Richard Hook
Public Information Officer, ESO

Garching bei München, Germany

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Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory
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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

Artist impression of the water snowline around the young star V883 Orionis, as detected with ALMA. Credit: A. Angelich (NRAO/AUI/NSF)/ALMA (ESO/NAOJ/NRAO).

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have produced the first image of a water snow line within a protoplanetary disk. This line marks where the temperature in the disk surrounding a young star drops sufficiently low for snow to form. A dramatic increase in the brightness of the young star V883 Orionis flash heated the inner portion of the disk, pushing the water snow line out to a far greater distance than is normal for a protostar, and making it possible to observe it for the first time. The results will be published in the journal Nature on July 14, 2016.

Image of the planet-forming disc around the young star V883 Orionis was obtained by ALMA in long-baseline mode. This star is currently in outburst, which has pushed the water snow line further from the star and allowed it to be detected for the first time. The dark ring midway through the disc is the water snowline, the point from the star where the temperature and pressure dip low enough for water ice to form. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

Young stars are often surrounded by dense, rotating disks of gas and dust, known as protoplanetary disks, from which planets are born. Snow lines are the regions in those disks where the temperature reaches the sublimation point for most of the volatile molecules. In the inner disk regions, inside water snow lines, water is vaporized, while outside these lines, in the outer disk, water is found frozen in the form of snow. These lines are so important that they define the basic architecture of planetary systems like our own [1] and are usually located for a typical solar-type star at around 3 au from the star [2].

However, the recent ALMA observations, to be published in Nature, show that the water snow line in V883 Orionis is currently at more than 40 au of the central star (corresponding to Neptune’s orbit in our system), greatly facilitating its detection [3]. This star is only thirty percent more massive than the Sun, but its luminosity is 400 times brighter as it’s currently experiencing what is known as a FU Ori outburst, a sudden increase in temperature and luminosity due to large amounts of material being transferred from the disk to the star [4]. This explains the displaced location of its water snow line: the disk has been flash-heated by the stellar outburst.

Lead author Lucas Cieza explains: “The ALMA observations came as a surprise to us. Our observations were designed to look for disk fragmentation leading to planet formation. We saw none of that; instead, we found what looks like a ring at 40 au. This illustrates well the transformational power of ALMA, which delivers exciting results even if they are not the ones we were looking for.”

The discovery that these outbursts may blast the water snow line to about 10 times its typical radius is very significant for the development of good planetary formation models. Such outbursts are believed to be a stage in the evolution of most planetary systems, so this may be the first observation of a common occurrence. In that case, this observation from ALMA could contribute significantly to a better understanding of how planets form and evolve throughout the Universe.

This illustration shows how the outburst of the young star V883 Orionis has displaced the water snowline much further out from the star, and rendered it detectable with ALMA. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

This image of the planet-forming disc around the young star V883 Orionis was obtained by ALMA in long-baseline mode. This star is currently in outburst, which has pushed the water snow line further from the star and allowed it to be detected for the first time. The dark ring midway through the disc is the water snowline, the point from the star where the temperature and pressure dip low enough for water ice to form. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

Notes

[1] In the solar nebula – which gave birth to our Solar System – this line was between the orbits of Mars and Jupiter during the formation of the Solar System, hence the rocky planets Mercury, Venus, Earth and Mars formed within the line, and the gaseous planets Jupiter, Saturn, Uranus and Neptune formed outside.

[2] 1 au, or one astronomical unit, is the mean distance between the Earth and the Sun, around 149.6 million kilometers. This unit is typically used to describe distances measured within the Solar System and planetary systems around other stars.

[3] Resolution is the ability to discern that objects are separate. To the human eye, several bright torches at a distance would seem like a single glowing spot, and only at closer quarters would each torch be distinguishable. The same principle applies to telescopes, and these new observations have exploited the exquisite resolution of ALMA in its long baseline modes. The resolution of ALMA at the distance of V883 Orionis is about 12 au — enough to resolve the water snow line at 40 au in this outbursting system, but not for a typical young star.

[4] Stars are believed to acquire most of their mass during these short but intense accretion events.

Additional information

These observation results were published in a paper entitled “Imaging the water snow-line during a protostellar outburst” to appear in the journal Nature on 14 July, 2016.

The research team is composed of Lucas A. Cieza [1,2], Simón Casassus [2,3], John Tobin [4], Steven Bos [4], Jonathan P. Williams [5], Sebastián Pérez [2,3], Zhaohuan Zhu [6], Claudio Cáceres [2,7], Héctor Cánovas [2,7], Michael M. Dunham [8], Antonio Hales [9], José L. Prieto [1], David A. Príncipe [1,2], Matthias R. Schreiber [2,7], Dary Ruiz-Rodríguez [10] and Alice Zurlo [1,2,3].

[1] Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Santiago, Chile.

[2] Millenium Nucleus “Protoplanetary Disks in ALMA Early Science”, Santiago, Chile.

[3] Departamento de Astronomía, Universidad de Chile, Santiago, Chile.

[4] Leiden Observatory, Leiden University, Leiden, The Netherlands.

[5] Institute for Astronomy, University of Hawaii at Manoa, Honolulu, USA.

[6] Department of Astrophysical Sciences, Princeton University, Princeton, USA.

[7] Departamento de Física y Astronomía, Universidad de Valparaíso, Valparaíso, Chile.

[8] Harvard-Smithsonian Center for Astrophysics, Cambridge, USA.


[9] Joint ALMA Observatory, Santiago, Chile.

[10] Australian National University, Mount Stromlo Observatory, Canberra, Australia.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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

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