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 Institute

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 L107

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/201014515

More information

Latest update

9/6/2018 1