Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI
Artikel i vetenskaplig tidskrift, 2010
Aims: We derive the dense core structure and the water abundance in four massive star-forming regions in the hope of understanding the earliest stages of massive star formation.
Methods: We present Herschel/HIFI observations of the para-H_2O 1_11-0_00 and 2_02-1_11 and the para-H\_2^18O 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 modeled with Monte-Carlo radiative transfer codes for dust and molecular lines (MC3D and RATRAN), and the water abundance and the turbulent velocity width as free parameters.
Results: 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 5\times10^-10 to 4\times10^-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.
Conclusions: The low H_2O 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.
Författare
M. G. Marseille
Netherlands Institute for Space Research (SRON)
F. F. S. van der Tak
Rijksuniversiteit Groningen
Netherlands Institute for Space Research (SRON)
F. Herpin
Institut National des Sciences de l'Univers
Laboratoire d'Astrophysique de Bordeaux
F. Wyrowski
Max-Planck-Gesellschaft
L. Chavarría
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
B. Pietropaoli
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
A. Baudry
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
S. Bontemps
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
J. Cernicharo
Centro de Astrobiologia (CAB)
T. Jacq
Osservatorio Astrofisico di Arcetri
W. Frieswijk
Netherlands Institute for Space Research (SRON)
R. Shipman
Netherlands Institute for Space Research (SRON)
E. F. van Dishoeck
Max-Planck-Gesellschaft
Universiteit Leiden
R. Bachiller
Observatorio Astronómico Nacional (OAN)
M. Benedettini
Universita degli Studi di Roma Tor Vergata
A. O. Benz
Eidgenössische Technische Hochschule Zürich (ETH)
E. A. Bergin
University of Michigan
Per Bjerkeli
Chalmers, Institutionen för radio- och rymdvetenskap, Radioastronomi och astrofysik
G. A. Blake
California Institute of Technology (Caltech)
J. Braine
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
S. Bruderer
Osservatorio Astrofisico di Arcetri
University of Leeds
P. Caselli
California Institute of Technology (Caltech)
Institut National des Sciences de l'Univers
Laboratoire d'Astrophysique de Bordeaux
E. Caux
Institut National des Sciences de l'Univers
Université de Toulouse
C. Codella
Osservatorio Astrofisico di Arcetri
F. Daniel
Centro de Astrobiologia (CAB)
P. Dieleman
Netherlands Institute for Space Research (SRON)
A. M. di Giorgio
Universita degli Studi di Roma Tor Vergata
C. Dominik
Radboud Universiteit
Anton Pannekoek Institute for Astronomy
S. Doty
Denison University
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. Fich
University of Waterloo
A. Fuente
Observatorio Astronómico Nacional (OAN)
T. Gaier
Jet Propulsion Laboratory, California Institute of Technology
T. Giannini
Osservatorio Astronomico di Roma
J. R. Goicoechea
Centro de Astrobiologia (CAB)
T. de Graauw
Netherlands Institute for Space Research (SRON)
F. Helmich
Netherlands Institute for Space Research (SRON)
G. J. Herczeg
Max-Planck-Gesellschaft
M. R. Hogerheijde
Universiteit Leiden
B. Jackson
Netherlands Institute for Space Research (SRON)
H. Javadi
Jet Propulsion Laboratory, California Institute of Technology
W. Jellema
Netherlands Institute for Space Research (SRON)
D. Johnstone
National Research Council Canada
University of Victoria
J. K. Jorgensen
Köpenhamns universitet
D. Kester
Netherlands Institute for Space Research (SRON)
L. Kristensen
Universiteit Leiden
B. Larsson
Stockholms universitet
W. Laauwen
Netherlands Institute for Space Research (SRON)
D. Lis
California Institute of Technology (Caltech)
René Liseau
Chalmers, Institutionen för radio- och rymdvetenskap, Radioastronomi och astrofysik
W. Luinge
Netherlands Institute for Space Research (SRON)
C. McCoey
Western University
University of Waterloo
A. Megej
Eidgenössische Technische Hochschule Zürich (ETH)
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
D. A. Neufeld
Johns Hopkins University
B. Nisini
Osservatorio Astronomico di Roma
Michael Olberg
Chalmers, Institutionen för radio- och rymdvetenskap, Nationella anläggningen för radioastronomi
B. Parise
Max-Planck-Gesellschaft
J. C. Pearson
Jet Propulsion Laboratory, California Institute of Technology
R. Plume
University of Calgary
C. Risacher
Netherlands Institute for Space Research (SRON)
P. Roelfsema
Netherlands Institute for Space Research (SRON)
J. Santiago-García
Institut de Radioastronomie Millimétrique (IRAM)
P. Saraceno
Universita degli Studi di Roma Tor Vergata
P. Siegel
Jet Propulsion Laboratory, California Institute of Technology
J. Stutzki
Universität zu Köln
M. Tafalla
Observatorio Astronómico Nacional (OAN)
T. A. van Kempen
Harvard-Smithsonian Center for Astrophysics
R. Visser
Universiteit Leiden
S. F. Wampfler
Eidgenössische Technische Hochschule Zürich (ETH)
U. A. Yildiz
Universiteit Leiden
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 L32+- L32Ämneskategorier
Astronomi, astrofysik och kosmologi
Fundament
Grundläggande vetenskaper
DOI
10.1051/0004-6361/201015103