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

Netherlands Institute for Space Research (SRON)

University of Groningen

F. Herpin

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

F. Wyrowski

Max Planck Institute

L. Chavarría

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

B. Pietropaoli

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

A. Baudry

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

S. Bontemps

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

J. Cernicharo

CSIC-INTA - 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

Leiden University

Max Planck Institute

R. Bachiller

Observatorio Astronomico Nacional

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

Caltech Division of Geological and Planetary Sciences

J. Braine

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

S. Bruderer

Arcetri Astrophysical Observatory

University of Leeds

P. Caselli

Institut National des Sciences de l'Univers

Caltech Division of Geological and Planetary Sciences

Laboratoire d'Astrophysique de Bordeaux

E. Caux

Universite de Toulouse

Institut National des Sciences de l'Univers

C. Codella

Arcetri Astrophysical Observatory

F. Daniel

CSIC-INTA - Centro de Astrobiologia (CAB)

P. Dieleman

Netherlands Institute for Space Research (SRON)

A. M. di Giorgio

University of Rome Tor Vergata

C. Dominik

Anton Pannekoek Institute for Astronomy

Radboud University

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

Observatorio Astronomico Nacional

T. Gaier

Jet Propulsion Laboratory, California Institute of Technology

T. Giannini

Osservatorio Astronomico di Roma

J. R. Goicoechea

CSIC-INTA - 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 Institute

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

Köbenhavns Universitet

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

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 Institute

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

Instituto de Radioastronomia Milimetrica

P. Saraceno

University of Rome Tor Vergata

P. Siegel

Jet Propulsion Laboratory, California Institute of Technology

J. Stutzki

University of Cologne

M. Tafalla

Observatorio Astronomico Nacional

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 L32+- L32

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1051/0004-6361/201015103