Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI
Artikel i vetenskaplig tidskrift, 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.

Författare

M. G. Marseille

SRON Netherlands Institute for Space Research

F. F. S. van der Tak

SRON Netherlands Institute for Space Research

University of Groningen, Kapteyn Astronomical Institute

F. Herpin

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

F. Wyrowski

Max Planck-institutet

L. Chavarría

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

B. Pietropaoli

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

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

Osservatorio Astrofisico di Arcetri

W. Frieswijk

SRON Netherlands Institute for Space Research

R. Shipman

SRON Netherlands Institute for Space Research

E. F. van Dishoeck

Leiden University

Max Planck-institutet

R. Bachiller

Observatorio Astronomico Nacional

M. Benedettini

Universita degli Studi di Roma Tor Vergata

A. O. Benz

Eidgenössische Technische Hochschule Zürich (ETH)

E. A. Bergin

University of Michigan

Per Bjerkeli

Chalmers, Institutionen för radio- och rymdvetenskap, Radioastronomi och astrofysik

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

University of Leeds

Osservatorio Astrofisico di Arcetri

P. Caselli

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

Caltech Division of Geological and Planetary Sciences

E. Caux

Institut National des Sciences de l'Univers

Universite de Toulouse

C. Codella

Osservatorio Astrofisico di Arcetri

F. Daniel

CSIC-INTA - Centro de Astrobiologia (CAB)

P. Dieleman

SRON Netherlands Institute for Space Research

A. M. di Giorgio

Universita degli Studi di Roma Tor Vergata

C. Dominik

Astronomical Institute Anton Pannekoek

Radboud Universiteit

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

SRON Netherlands Institute for Space Research

F. Helmich

SRON Netherlands Institute for Space Research

G. J. Herczeg

Max Planck-institutet

M. R. Hogerheijde

Leiden University

B. Jackson

SRON Netherlands Institute for Space Research

H. Javadi

Jet Propulsion Laboratory, California Institute of Technology

W. Jellema

SRON Netherlands Institute for Space Research

D. Johnstone

National Research Council Canada

University of Victoria

J. K. Jorgensen

Kobenhavns Universitet

D. Kester

SRON Netherlands Institute for Space Research

L. Kristensen

Leiden University

B. Larsson

Stockholms universitet

W. Laauwen

SRON Netherlands Institute for Space Research

D. Lis

CalTech

René Liseau

Chalmers, Institutionen för radio- och rymdvetenskap, Radioastronomi och astrofysik

W. Luinge

SRON Netherlands Institute for Space Research

C. McCoey

University of Waterloo

Western University

A. Megej

Eidgenössische Technische Hochschule 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, Institutionen för radio- och rymdvetenskap, Nationella anläggningen för radioastronomi

B. Parise

Max Planck-institutet

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

R. Plume

University of Calgary

C. Risacher

SRON Netherlands Institute for Space Research

P. Roelfsema

SRON Netherlands Institute for Space Research

J. Santiago-García

Instituto de Radioastronomia Milimetrica

P. Saraceno

Universita degli Studi di Roma Tor Vergata

P. Siegel

Jet Propulsion Laboratory, California Institute of Technology

J. Stutzki

Universität zu Köln

M. Tafalla

Observatorio Astronomico Nacional

T. A. van Kempen

Harvard-Smithsonian Center for Astrophysics

R. Visser

Leiden University

S. F. Wampfler

Eidgenössische Technische Hochschule Zürich (ETH)

U. A. Yildiz

Leiden University

Astronomy and Astrophysics

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

Vol. 521 L32+- L32

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

DOI

10.1051/0004-6361/201015103