Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI
Journal article, 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.
Author
M. G. Marseille
Netherlands Institute for Space Research (SRON)
F. F. S. van der Tak
University of 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 Society
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
Arcetri Astrophysical Observatory
W. Frieswijk
Netherlands Institute for Space Research (SRON)
R. Shipman
Netherlands Institute for Space Research (SRON)
E. F. van Dishoeck
Max Planck Society
Leiden University
R. Bachiller
Spanish National Observatory (OAN)
M. Benedettini
University of Rome Tor Vergata
A. O. Benz
Swiss Federal Institute of Technology in Zürich (ETH)
E. A. Bergin
University of Michigan
Per Bjerkeli
Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics
G. A. Blake
California Institute of Technology (Caltech)
J. Braine
Laboratoire d'Astrophysique de Bordeaux
Institut National des Sciences de l'Univers
S. Bruderer
Arcetri Astrophysical Observatory
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
University of Toulouse
C. Codella
Arcetri Astrophysical Observatory
F. Daniel
Centro de Astrobiologia (CAB)
P. Dieleman
Netherlands Institute for Space Research (SRON)
A. M. di Giorgio
University of Rome Tor Vergata
C. Dominik
Radboud University
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
Spanish National Observatory (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 Society
M. R. Hogerheijde
Leiden University
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
University of Copenhagen
D. Kester
Netherlands Institute for Space Research (SRON)
L. Kristensen
Leiden University
B. Larsson
Stockholm University
W. Laauwen
Netherlands Institute for Space Research (SRON)
D. Lis
California Institute of Technology (Caltech)
René Liseau
Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics
W. Luinge
Netherlands Institute for Space Research (SRON)
C. McCoey
Western University
University of Waterloo
A. Megej
Swiss Federal Institute of Technology in 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, Department of Radio and Space Science, National Facility for Radio Astronomy
B. Parise
Max Planck Society
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
University of Rome Tor Vergata
P. Siegel
Jet Propulsion Laboratory, California Institute of Technology
J. Stutzki
University of Cologne
M. Tafalla
Spanish National Observatory (OAN)
T. A. van Kempen
Harvard-Smithsonian Center for Astrophysics
R. Visser
Leiden University
S. F. Wampfler
Swiss Federal Institute of Technology in Zürich (ETH)
U. A. Yildiz
Leiden University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 L32+- L32Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
DOI
10.1051/0004-6361/201015103