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Water in star-formi...
Water in star-forming regions: Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
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- van Dishoeck, E. F. (författare)
- Universiteit Leiden (UL),Leiden University (UL),Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG),Osservatorio Astrofisico di Arcetri,Arcetri Astrophysical Observatory
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- Kristensen, L. E. (författare)
- Niels Bohr Institute
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- Mottram, J. C. (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG),CSIC - Instituto de Fisica Fundamental (IFF)
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visa fler...
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- Benz, A. O. (författare)
- Eidgenössische Technische Hochschule Zürich (ETH),Swiss Federal Institute of Technology in Zürich (ETH)
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- Bergin, E. A. (författare)
- University of Michigan
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- Caselli, P. (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Herpin, F. (författare)
- Université de Bordeaux,University of Bordeaux
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- Hogerheijde, M. (författare)
- Universiteit Leiden (UL),Leiden University (UL),Universiteit Van Amsterdam,University of Amsterdam
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- Johnstone, D. (författare)
- University of Victoria,National Research Council Canada
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- Liseau, René, 1949 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Nisini, B. (författare)
- Osservatorio Astronomico di Roma
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- Tafalla, M. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN)
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- van der Tak, F. F. S. (författare)
- Rijksuniversiteit Groningen,University of Groningen,Netherlands Institute for Space Research (SRON)
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- Wyrowski, F. (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Baudry, A. (författare)
- Université de Bordeaux,University of Bordeaux
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- Benedettini, M. (författare)
- Istituto nazionale di astrofisica (INAF)
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- Bjerkeli, Per, 1977 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Blake, G. A. (författare)
- California Institute of Technology (Caltech)
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- Braine, J. (författare)
- Université de Bordeaux,University of Bordeaux
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- Bruderer, S. (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG),Eidgenössische Technische Hochschule Zürich (ETH),Swiss Federal Institute of Technology in Zürich (ETH)
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- Cabrit, S. (författare)
- Observatoire de Paris,Paris Observatory
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- Cernicharo, Jose (författare)
- CSIC - Instituto de Fisica Fundamental (IFF)
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- Choi, Yunhee (författare)
- Netherlands Institute for Space Research (SRON),Korea Astronomy and Space Science Institute
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- Coutens, A. (författare)
- Université de Bordeaux,University of Bordeaux
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- de Graauw, T. (författare)
- Netherlands Institute for Space Research (SRON),Universiteit Leiden (UL),Leiden University (UL)
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- Dominik, C. (författare)
- Universiteit Van Amsterdam,University of Amsterdam
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- Fedele, D. (författare)
- Osservatorio Astrofisico di Arcetri,Arcetri Astrophysical Observatory
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- Fich, M. (författare)
- University of Waterloo
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- Fuente, A. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN)
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- Furuya, Kenji (författare)
- National Astronomical Observatory of Japan
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- Goicoechea, J.R. (författare)
- CSIC - Instituto de Fisica Fundamental (IFF)
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- Harsono, D. (författare)
- Universiteit Leiden (UL),Leiden University (UL)
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- Helmich, F. (författare)
- Netherlands Institute for Space Research (SRON),Rijksuniversiteit Groningen,University of Groningen
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- Herczeg, G. J. (författare)
- Beijing University of Technology
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- Jacq, T. (författare)
- Université de Bordeaux,University of Bordeaux
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- Karska, A. (författare)
- Uniwersytet Mikolaja Kopernika w Toruniu,Nicolaus Copernicus University
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- Kaufman, M. (författare)
- San Jose State University
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- Keto, E. (författare)
- Harvard-Smithsonian Center for Astrophysics
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- Lamberts, T. (författare)
- Leiden Institute of Chemistry
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- Larsson, Bengt (författare)
- Stockholms universitet,Institutionen för astronomi,Stockholm University
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- Leurini, S. (författare)
- Istituto nazionale di astrofisica (INAF),Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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Lis, D. C. (författare)
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- Melnick, G. J. (författare)
- Harvard-Smithsonian Center for Astrophysics
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- Neufeld, D.A. (författare)
- Johns Hopkins University
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- Pagani, L. (författare)
- Observatoire de Paris,Paris Observatory
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- Persson, Magnus V., 1983 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Shipman, R. (författare)
- Netherlands Institute for Space Research (SRON)
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- Taquet, V. (författare)
- Osservatorio Astrofisico di Arcetri,Arcetri Astrophysical Observatory,Netherlands Institute for Space Research (SRON)
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- van Kempen, T. A. (författare)
- Netherlands Institute for Space Research (SRON)
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- Walsh, C. (författare)
- University of Leeds
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- Wampfler, S. F. (författare)
- Universität Bern,University of Bern
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Ylldlz, U. (författare)
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Universiteit Leiden (UL) Max Planck Gesellschaft zur Förderung der Wissenschaften eV. (MPG) (creator_code:org_t)
- 2021-04-09
- 2021
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 648
- Relaterad länk:
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https://research.cha... (primary) (free)
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https://www.aanda.or...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Context. Water is a key molecule in the physics and chemistry of star and planet formation, but it is difficult to observe from Earth. The Herschel Space Observatory provided unprecedented sensitivity as well as spatial and spectral resolution to study water. The Water In Star-forming regions with Herschel (WISH) key program was designed to observe water in a wide range of environments and provide a legacy data set to address its physics and chemistry. Aims. The aim of WISH is to determine which physical components are traced by the gas-phase water lines observed with Herschel and to quantify the excitation conditions and water abundances in each of these components. This then provides insight into how and where the bulk of the water is formed in space and how it is transported from clouds to disks, and ultimately comets and planets. Methods. Data and results from WISH are summarized together with those from related open time programs. WISH targeted ∼80 sources along the two axes of luminosity and evolutionary stage: from low- to high-mass protostars (luminosities from <1 to > 10Lpdbl) and from pre-stellar cores to protoplanetary disks. Lines of H2O and its isotopologs, HDO, OH, CO, and [O I], were observed with the HIFI and PACS instruments, complemented by other chemically-related molecules that are probes of ultraviolet, X-ray, or grain chemistry. The analysis consists of coupling the physical structure of the sources with simple chemical networks and using non-LTE radiative transfer calculations to directly compare models and observations. Results. Most of the far-infrared water emission observed with Herschel in star-forming regions originates from warm outflowing and shocked gas at a high density and temperature (> 10cm-3, 300-1000 K, v ∼ 25 km s-1), heated by kinetic energy dissipation. This gas is not probed by single-dish low-J CO lines, but only by CO lines with Jup > 14. The emission is compact, with at least two different types of velocity components seen. Water is a significant, but not dominant, coolant of warm gas in the earliest protostellar stages. The warm gas water abundance is universally low: orders of magnitude below the H2O/H2 abundance of 4 × 10-4 expected if all volatile oxygen is locked in water. In cold pre-stellar cores and outer protostellar envelopes, the water abundance structure is uniquely probed on scales much smaller than the beam through velocity-resolved line profiles. The inferred gaseous water abundance decreases with depth into the cloud with an enhanced layer at the edge due to photodesorption of water ice. All of these conclusions hold irrespective of protostellar luminosity. For low-mass protostars, a constant gaseous HDO/H2O ratio of ∼0.025 with position into the cold envelope is found. This value is representative of the outermost photodesorbed ice layers and cold gas-phase chemistry, and much higher than that of bulk ice. In contrast, the gas-phase NH3 abundance stays constant as a function of position in low-mass pre- and protostellar cores. Water abundances in the inner hot cores are high, but with variations from 5 × 10-6 to a few × 10-4 for low- and high-mass sources. Water vapor emission from both young and mature disks is weak. Conclusions. The main chemical pathways of water at each of the star-formation stages have been identified and quantified. Low warm water abundances can be explained with shock models that include UV radiation to dissociate water and modify the shock structure. UV fields up to 102-10times the general interstellar radiation field are inferred in the outflow cavity walls on scales of the Herschel beam from various hydrides. Both high temperature chemistry and ice sputtering contribute to the gaseous water abundance at low velocities, with only gas-phase (re-)formation producing water at high velocities. Combined analyses of water gas and ice show that up to 50% of the oxygen budget may be missing. In cold clouds, an elegant solution is that this apparently missing oxygen is locked up in larger μm-sized grains that do not contribute to infrared ice absorption. The fact that even warm outflows and hot cores do not show H2O at full oxygen abundance points to an unidentified refractory component, which is also found in diffuse clouds. The weak water vapor emission from disks indicates that water ice is locked up in larger pebbles early on in the embedded Class I stage and that these pebbles have settled and drifted inward by the Class II stage. Water is transported from clouds to disks mostly as ice, with no evidence for strong accretion shocks. Even at abundances that are somewhat lower than expected, many oceans of water are likely present in planet-forming regions. Based on the lessons for galactic protostars, the low-J H2O line emission (Eup < 300 K) observed in extragalactic sources is inferred to be predominantly collisionally excited and to originate mostly from compact regions of current star formation activity. Recommendations for future mid- to far-infrared missions are made.
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Samhällsbyggnadsteknik -- Vattenteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Civil Engineering -- Water Engineering (hsv//eng)
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Nyckelord
- ISM: molecules
- Astrochemistry
- Protoplanetary disks
- ISM: jets and outflows
- Stars: formation
- Infrared: ISM
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
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Till lärosätets databas
- Av författaren/redakt...
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van Dishoeck, E. ...
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Kristensen, L. E ...
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Mottram, J. C.
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Benz, A. O.
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Bergin, E. A.
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Caselli, P.
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visa fler...
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Herpin, F.
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Hogerheijde, M.
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Johnstone, D.
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Liseau, René, 19 ...
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Nisini, B.
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Tafalla, M.
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van der Tak, F. ...
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Wyrowski, F.
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Baudry, A.
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Benedettini, M.
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Bjerkeli, Per, 1 ...
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Blake, G. A.
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Braine, J.
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Bruderer, S.
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Cabrit, S.
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Cernicharo, Jose
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Choi, Yunhee
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Coutens, A.
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de Graauw, T.
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Dominik, C.
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Fedele, D.
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Fich, M.
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Fuente, A.
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Furuya, Kenji
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Goicoechea, J.R.
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Harsono, D.
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Helmich, F.
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Herczeg, G. J.
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Jacq, T.
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Karska, A.
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Kaufman, M.
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Keto, E.
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Lamberts, T.
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Larsson, Bengt
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Leurini, S.
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Lis, D. C.
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Melnick, G. J.
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Neufeld, D.A.
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Pagani, L.
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Persson, Magnus ...
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Shipman, R.
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Taquet, V.
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van Kempen, T. A ...
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Walsh, C.
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Wampfler, S. F.
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Ylldlz, U.
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NATURVETENSKAP
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Chalmers tekniska högskola
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Stockholms universitet