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.

ISM: molecules

astrochemistry

stars: formation

star-formation

evolution

young stars

monte-carlo method

excitation

ISM: individual

absorption

line emission

h-2

objects: DR21

cygnus-x

radiative-transfer

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

MPI fur Extraterrestrische Physik

Universiteit Leiden

A. O. Benz

Eidgenössische Technische Hochschule Zürich (ETH)

P. Caselli

University of Leeds

M. Hogerheijde

Universiteit Leiden

D. Johnstone

University of Victoria

National Research Council Canada

René Liseau

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

R. Bachiller

Observatorio Astronomico Nacional

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

CalTech

S. Bruderer

Eidgenössische Technische Hochschule Zürich (ETH)

J. Cernicharo

CSIC-INTA - Centro de Astrobiologia (CAB)

C. Codella

Istituto di Fisica dello Spazio Interplanetario, Rome

F. Daniel

Observatoire de Paris-Meudon

CSIC-INTA - Centro de Astrobiologia (CAB)

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 Astronomico Nacional

T. Giannini

Istituto di Fisica dello Spazio Interplanetario, Rome

J. R. Goicoechea

CSIC-INTA - Centro de Astrobiologia (CAB)

T. de Graauw

Atacama Large Millimeter-submillimeter Array

F. Helmich

Netherlands Institute for Space Research (SRON)

G. J. Herczeg

MPI fur Extraterrestrische Physik

J. K. Jorgensen

Köbenhavns Universitet

L. Kristensen

Universiteit Leiden

B. Larsson

Stockholms universitet

D. Lis

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-institutet

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

Observatorio Astronomico Nacional

P. Saraceno

Istituto di Fisica dello Spazio Interplanetario, Rome

M. Tafalla

Observatorio Astronomico Nacional

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

Universite de Toulouse

P. Roelfsema

Netherlands Institute for Space Research (SRON)

O. Siebertz

Universität zu Köln

D. Teyssier

European Space Astronomy Centre

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 518 L107

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201014515