Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI

Autor: M. G. Marseille, F. F. S. van der Tak, F. Herpin, F. Wyrowski, L. Chavarría, B. Pietropaoli, A. Baudry, S. Bontemps, J. Cernicharo, T. Jacq, W. Frieswijk, R. Shipman, E. F. van Dishoeck, R. Bachiller, M. Benedettini, A. O. Benz, E. Bergin, P. Bjerkeli, G. A. Blake, J. Braine, S. Bruderer, P. Caselli, E. Caux, C. Codella, F. Daniel, P. Dieleman, A. M. di Giorgio, C. Dominik, S. D. Doty, P. Encrenaz, M. Fich, A. Fuente, T. Gaier, T. Giannini, J. R. Goicoechea, Th. de Graauw, F. Helmich, G. J. Herczeg, M. R. Hogerheijde, B. Jackson, H. Javadi, W. Jellema, D. Johnstone, J. K. Jørgensen, D. Kester, L. E. Kristensen, B. Larsson, W. Laauwen, D. Lis, R. Liseau, W. Luinge, C. McCoey, A. Megej, G. Melnick, D. Neufeld, B. Nisini, M. Olberg, B. Parise, J. C. Pearson, R. Plume, C. Risacher, P. Roelfsema, J. Santiago-García, P. Saraceno, P. Siegel, J. Stutzki, M. Tafalla, T. A. van Kempen, R. Visser, S. F. Wampfler, U. A. Yıldız
Přispěvatelé: Low Energy Astrophysics (API, FNWI), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, SRON Netherlands Institute for Space Research (SRON), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Max-Planck-Institut für Radioastronomie (MPIFR), Astronomy
Jazyk: angličtina
Rok vydání: 2010
Předmět:
010504 meteorology & atmospheric sciences
Astronomy
FOS: Physical sciences
Astrophysics
01 natural sciences
ISM: abundances
STAR-FORMATION
REGION
RADIATIVE-TRANSFER
Abundance (ecology)
EXCITATION
0103 physical sciences
Radiative transfer
H2O
Protostar
Absorption (electromagnetic radiation)
010303 astronomy & astrophysics
QB
0105 earth and related environmental sciences
Envelope (waves)
Line (formation)
Physics
Line-of-sight
extinction
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Star formation
Research Programm of Institute for Mathematics
Astrophysics and Particle Physics
MONTE-CARLO METHOD
PROTOSTARS
CORES
Astronomy and Astrophysics
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Astrophysics - Astrophysics of Galaxies
ISM: molecules
EVOLUTION
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
ComputingMethodologies_DOCUMENTANDTEXTPROCESSING
dust
extinction
dust
EMISSION
Galaxy Astrophysics
Zdroj: Astronomy & Astrophysics, 521, L32
Astronomy & Astrophysics, 521. EDP Sciences
Astronomy & Astrophysics, 521, pp. L32
Astronomy and Astrophysics-A&A
Astronomy and Astrophysics-A&A, EDP Sciences, 2010, 521, pp.L32. ⟨10.1051/0004-6361/201015103⟩
Astronomy & astrophysics, 521:L32. EDP Sciences
ISSN: 0004-6361
Popis: We derive the dense core structure and the water abundance in four massive star-forming regions which may help understand the earliest stages of massive star formation. We present Herschel-HIFI observations of the para-H2O 1_11-0_00 and 2_02-1_11 and the para-H2-18O 1_11-0_00 transitions. The envelope contribution to the line profiles is separated from contributions by outflows and foreground clouds. The envelope contribution is modelled using Monte-Carlo radiative transfer codes for dust and molecular lines (MC3D and RATRAN), with the water abundance and the turbulent velocity width as free parameters. While the outflows are mostly seen in emission in high-J lines, envelopes are seen in absorption in ground-state lines, which are almost saturated. The derived water abundances range from 5E-10 to 4E-8 in the outer envelopes. We detect cold clouds surrounding the protostar envelope, thanks to the very high quality of the Herschel-HIFI data and the unique ability of water to probe them. Several foreground clouds are also detected along the line of sight. The low H2O abundances in massive dense cores are in accordance with the expectation that high densities and low temperatures lead to freeze-out of water on dust grains. The spread in abundance values is not clearly linked to physical properties of the sources.
Comment: 8 pages, 5 figures, accepted for publication the 15/07/2010 by Astronomy&Astrophysics as a letter in the Herschel-HIFI special issue
Databáze: OpenAIRE
Externí odkaz: