Water abundance variations around high-mass protostars: HIFI observations of the DR21 region
Journal article, 2010
Context. Water is a key molecule in the star formation process, but its spatial distribution in star-forming regions is not well known. Aims. We study the distribution of dust continuum and H2O and (CO)-C-13 line emission in DR21, a luminous star-forming region with a powerful outflow and a compact H II region. Methods. Herschel-HIFI spectra near 1100 GHz show narrow (CO)-C-13 10-9 emission and H2O 1(11)-0(00) absorption from the dense core and broad emission from the outflow in both lines. The H2O line also shows absorption by a foreground cloud known from ground-based observations of low-J CO lines. Results. The dust continuum emission is extended over 36 '' FWHM, while the (CO)-C-13 and H2O lines are confined to approximate to 24 '' or less. The foreground absorption appears to peak further North than the other components. Radiative transfer models indicate very low abundances of similar to 2 x 10(-10) for H2O and similar to 8 x 10(-7) for (CO)-C-13 in the dense core, and higher H2O abundances of similar to 4 x 10(-9) in the foreground cloud and similar to 7 x 10(-7) in the outflow. Conclusions. The high H2O abundance in the warm outflow is probably due to the evaporation of water-rich icy grain mantles, while the H2O abundance is kept down by freeze-out in the dense core and by photodissociation in the foreground cloud.
evolution
monte-carlo method
ISM: individual
radiative-transfer
young stars
stars: formation
cygnus-x
astrochemistry
absorption
star-formation
excitation
line emission
ISM: molecules
h-2
objects: DR21
Author
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
University of Groningen
M. G. Marseille
Netherlands Institute for Space Research (SRON)
F. Herpin
Laboratoire d'Astrophysique de Bordeaux
F. Wyrowski
Netherlands Institute for Space Research (SRON)
A. Baudry
Laboratoire d'Astrophysique de Bordeaux
S. Bontemps
Laboratoire d'Astrophysique de Bordeaux
J. Braine
Laboratoire d'Astrophysique de Bordeaux
S. Doty
Denison University
W. Frieswijk
University of Groningen
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
R. Shipman
Netherlands Institute for Space Research (SRON)
E. F. van Dishoeck
MPI fur Extraterrestrische Physik
Leiden University
A. O. Benz
Swiss Federal Institute of Technology in Zürich (ETH)
P. Caselli
University of Leeds
M. Hogerheijde
Leiden University
D. Johnstone
National Research Council Canada
University of Victoria
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
R. Bachiller
Spanish National Observatory (OAN)
M. Benedettini
Istituto di Fisica dello Spazio Interplanetario, Rome
E. A. Bergin
University of Michigan
Per Bjerkeli
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
G. A. Blake
California Institute of Technology (Caltech)
S. Bruderer
Swiss Federal Institute of Technology in Zürich (ETH)
J. Cernicharo
Centro de Astrobiologia (CAB)
C. Codella
Istituto di Fisica dello Spazio Interplanetario, Rome
F. Daniel
Observatoire de Paris-Meudon
Centro de Astrobiologia (CAB)
A. M. di Giorgio
Istituto di Fisica dello Spazio Interplanetario, Rome
C. Dominik
University of Amsterdam
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. Giannini
Istituto di Fisica dello Spazio Interplanetario, Rome
J. R. Goicoechea
Centro de Astrobiologia (CAB)
T. de Graauw
Atacama Large Millimeter-submillimeter Array (ALMA)
F. Helmich
Netherlands Institute for Space Research (SRON)
G. J. Herczeg
MPI fur Extraterrestrische Physik
J. K. Jorgensen
University of Copenhagen
L. Kristensen
Leiden University
B. Larsson
Stockholm University
D. Lis
California Institute of Technology (Caltech)
C. McCoey
University of Waterloo
D. A. Neufeld
Johns Hopkins University
B. Nisini
Istituto di Fisica dello Spazio Interplanetario, Rome
Michael Olberg
Chalmers, Earth and Space Sciences, Onsala Space Observatory
B. Parise
University of Cologne
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)
J. Santiago
Spanish National Observatory (OAN)
P. Saraceno
Istituto di Fisica dello Spazio Interplanetario, Rome
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
L. Ravera
University of Toulouse
P. Roelfsema
Netherlands Institute for Space Research (SRON)
O. Siebertz
University of Cologne
D. Teyssier
European Space Astronomy Centre (ESAC)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 Article Number: L107 L107Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014515