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Water in star-formi...
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Mottram, J. C.Universiteit Leiden (UL),Leiden University (UL)
(författare)
Water in star-forming regions with Herschel (WISH)
- Artikel/kapitelEngelska2014
Förlag, utgivningsår, omfång ...
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2014-11-21
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EDP Sciences,2014
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electronicrdacarrier
Nummerbeteckningar
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LIBRIS-ID:oai:research.chalmers.se:b218f0a7-3bcd-4c2c-ade0-2fa94b7a7847
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https://doi.org/10.1051/0004-6361/201424267DOI
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https://research.chalmers.se/publication/210898URI
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Språk:engelska
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Sammanfattning på:engelska
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Ämneskategori:art swepub-publicationtype
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Ämneskategori:ref swepub-contenttype
Anmärkningar
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Context. Outflows are an important part of the star formation process as both the result of ongoing active accretion and one of the main sources of mechanical feedback on small scales. Water is the ideal tracer of these effects because it is present in high abundance for the conditions expected in various parts of the protostar, particularly the outflow. Aims. We constrain and quantify the physical conditions probed by water in the outflow-jet system for Class 0 and I sources. Methods. We present velocity-resolved Herschel HIFI spectra of multiple water-transitions observed towards 29 nearby Class 0/I protostars as part of the WISH guaranteed time key programme. The lines are decomposed into different Gaussian components, with each component related to one of three parts of the protostellar system; quiescent envelope, cavity shock and spot shocks in the jet and at the base of the outflow. We then use non-LTE radex models to constrain the excitation conditions present in the two outflow-related components. Results. Water emission at the source position is optically thick but effectively thin, with line ratios that do not vary with velocity, in contrast to CO. The physical conditions of the cavity and spot shocks are similar, with post-shock H-2 densities of order 10(5) -10(8) cm(-3) and H2O column densities of order 10(16) -10(18) cm(-2). H2O emission originates in compact emitting regions: for the spot shocks these correspond to point sources with radii of order 10-200 AU, while for the cavity shocks these come from a thin layer along the outflow cavity wall with thickness of order 1-30 AU. Conclusions. Water emission at the source position traces two distinct kinematic components in the outflow; J shocks at the base of the outflow or in the jet, and C shocks in a thin layer in the cavity wall. The similarity of the physical conditions is in contrast to off-source determinations which show similar densities but lower column densities and larger filling factors. We propose that this is due to the differences in shock properties and geometry between these positions. Class I sources have similar excitation conditions to Class 0 sources, but generally smaller line-widths and emitting region sizes. We suggest that it is the velocity of the wind driving the outflow, rather than the decrease in envelope density or mass, that is the cause of the decrease in H2O intensity between Class 0 and I sources.
Ämnesord och genrebeteckningar
Biuppslag (personer, institutioner, konferenser, titlar ...)
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Kristensen, L.Harvard-Smithsonian Center for Astrophysics
(författare)
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van Dishoeck, E. F.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)
(författare)
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Bruderer, S.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
(författare)
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San Jose-Garcia, I.Universiteit Leiden (UL),Leiden University (UL)
(författare)
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Karska, A.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
(författare)
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Visser, R.University of Michigan
(författare)
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Santangelo, G.Osservatorio Astrofisico di Arcetri,Arcetri Astrophysical Observatory,Osservatorio Astronomico di Roma
(författare)
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Benz, A. O.Eidgenössische Technische Hochschule Zürich (ETH),Swiss Federal Institute of Technology in Zürich (ETH)
(författare)
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Bergin, E. A.University of Michigan
(författare)
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Caselli, P.University of Leeds,Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
(författare)
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Herpin, F.Université de Bordeaux,University of Bordeaux,Laboratoire d'Astrophysique de Bordeaux
(författare)
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Hogerheijde, M. R.Universiteit Leiden (UL),Leiden University (UL)
(författare)
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Johnstone, D.National Research Council Canada,University of Victoria
(författare)
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van Kempen, T. A.Universiteit Leiden (UL),Leiden University (UL)
(författare)
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Liseau, René,1949Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)liseau
(författare)
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Nisini, B.Osservatorio Astronomico di Roma
(författare)
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Tafalla, M.
(författare)
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van der Tak, F. F. S.Rijksuniversiteit Groningen,University of Groningen,Netherlands Institute for Space Research (SRON)
(författare)
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Wyrowski, F.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
(författare)
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Universiteit Leiden (UL)Harvard-Smithsonian Center for Astrophysics
(creator_code:org_t)
Sammanhörande titlar
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Ingår i:Astronomy and Astrophysics: EDP Sciences5720004-63611432-0746
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Mottram, J. C.
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Kristensen, L.
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van Dishoeck, E. ...
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Bruderer, S.
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San Jose-Garcia, ...
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Karska, A.
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visa fler...
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Visser, R.
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Santangelo, G.
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Benz, A. O.
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Bergin, E. A.
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Caselli, P.
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Herpin, F.
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Hogerheijde, M. ...
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Johnstone, D.
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van Kempen, T. A ...
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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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