Water abundance variations around high-mass protostars: HIFI observations of the DR21 region
Artikel i vetenskaplig tidskrift, 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.
h-2
monte-carlo method
ISM: individual
line emission
objects: DR21
stars: formation
evolution
young stars
radiative-transfer
ISM: molecules
star-formation
excitation
absorption
cygnus-x
astrochemistry
Författare
F. F. S. van der Tak
Rijksuniversiteit Groningen
Netherlands Institute for Space Research (SRON)
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
Rijksuniversiteit Groningen
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
R. Shipman
Netherlands Institute for Space Research (SRON)
E. F. van Dishoeck
Universiteit Leiden
MPI fur Extraterrestrische Physik
A. O. Benz
Eidgenössische Technische Hochschule Zürich (ETH)
P. Caselli
University of Leeds
M. Hogerheijde
Universiteit Leiden
D. Johnstone
National Research Council Canada
University of Victoria
René Liseau
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
R. Bachiller
Observatorio Astronómico Nacional (OAN)
M. Benedettini
Istituto di Fisica dello Spazio Interplanetario, Rome
E. A. Bergin
University of Michigan
Per Bjerkeli
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
G. A. Blake
California Institute of Technology (Caltech)
S. Bruderer
Eidgenössische Technische Hochschule Zürich (ETH)
J. Cernicharo
Centro de Astrobiologia (CAB)
C. Codella
Istituto di Fisica dello Spazio Interplanetario, Rome
F. Daniel
Centro de Astrobiologia (CAB)
Observatoire de Paris-Meudon
A. M. di Giorgio
Istituto di Fisica dello Spazio Interplanetario, Rome
C. Dominik
Universiteit Van Amsterdam
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. 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
Köpenhamns universitet
L. Kristensen
Universiteit Leiden
B. Larsson
Stockholms universitet
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, Rymd- och geovetenskap, Onsala rymdobservatorium
B. Parise
Universität zu Köln
Max-Planck-Gesellschaft
J. C. Pearson
California Institute of Technology (Caltech)
R. Plume
University of Calgary
C. Risacher
Netherlands Institute for Space Research (SRON)
J. Santiago
Observatorio Astronómico Nacional (OAN)
P. Saraceno
Istituto di Fisica dello Spazio Interplanetario, Rome
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
L. Ravera
Université de Toulouse
P. Roelfsema
Netherlands Institute for Space Research (SRON)
O. Siebertz
Universität zu Köln
D. Teyssier
Europeiska rymdorganisationen (ESA)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 Article Number: L107 L107Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201014515