Water cooling of shocks in protostellar outflows Herschel-PACS map of L1157
Artikel i vetenskaplig tidskrift, 2010
Context. The far-IR/sub-mm spectral mapping facility provided by the Herschel-PACS and HIFI instruments has made it possible to obtain, for the first time, images of H2O emission with a spatial resolution comparable to ground based mm/sub-mm observations. Aims. In the framework of the Water In Star-forming regions with Herschel (WISH) key program, maps in water lines of several outflows from young stars are being obtained, to study the water production in shocks and its role in the outflow cooling. This paper reports the first results of this program, presenting a PACS map of the o-H2O 179 mu m transition obtained toward the young outflow L1157. Methods. The 179 mu m map is compared with those of other important shock tracers, and with previous single-pointing ISO, SWAS, and Odin water observations of the same source that allow us to constrain the H2O abundance and total cooling. Results. Strong H2O peaks are localized on both shocked emission knots and the central source position. The H2O 179 mu m emission is spatially correlated with emission from H-2 rotational lines, excited in shocks leading to a significant enhancement of the water abundance. Water emission peaks along the outflow also correlate with peaks of other shock-produced molecular species, such as SiO and NH3. A strong H2O peak is also observed at the location of the proto-star, where none of the other molecules have significant emission. The absolute 179 mu m intensity and its intensity ratio to the H2O 557 GHz line previously observed with Odin/SWAS indicate that the water emission originates in warm compact clumps, spatially unresolved by PACS, having a H2O abundance of the order of 10(-4). This testifies that the clumps have been heated for a time long enough to allow the conversion of almost all the available gas-phase oxygen into water. The total H2O cooling is similar to 10(-1) L-circle dot, about 40% of the cooling due to H-2 and 23% of the total energy released in shocks along the L1157 outflow.
ISM: jets and outflows
emission
class-0 sources
stars: formation
swas
ISM: molecules
gas
Författare
B. Nisini
Osservatorio Astronomico di Roma
M. Benedettini
Istituto di Fisica dello Spazio Interplanetario, Rome
C. Codella
Osservatorio Astrofisico di Arcetri
T. Giannini
Osservatorio Astronomico di Roma
René Liseau
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
D. A. Neufeld
Johns Hopkins University
M. Tafalla
Observatorio Astronómico Nacional (OAN)
E. F. van Dishoeck
Universiteit Leiden
Max-Planck-Gesellschaft
R. Bachiller
Observatorio Astronómico Nacional (OAN)
A. Baudry
Laboratoire d'Astrophysique de Bordeaux
A. O. Benz
Eidgenössische Technische Hochschule Zürich (ETH)
E. A. Bergin
University of Michigan
Per Bjerkeli
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
G. A. Blake
California Institute of Technology (Caltech)
S. Bontemps
Laboratoire d'Astrophysique de Bordeaux
J. Braine
Laboratoire d'Astrophysique de Bordeaux
S. Bruderer
Eidgenössische Technische Hochschule Zürich (ETH)
P. Caselli
Osservatorio Astrofisico di Arcetri
University of Leeds
J. Cernicharo
Centro de Astrobiologia (CAB)
F. Daniel
Centro de Astrobiologia (CAB)
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
A. M. di Giorgio
Istituto di Fisica dello Spazio Interplanetario, Rome
C. Dominik
Anton Pannekoek Institute for Astronomy
Radboud Universiteit
S. Doty
Denison University
M. Fich
University of Waterloo
A. Fuente
Observatorio Astronómico Nacional (OAN)
J. R. Goicoechea
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-Gesellschaft
F. Herpin
Laboratoire d'Astrophysique de Bordeaux
M. Hogerheijde
Universiteit Leiden
T. Jacq
Laboratoire d'Astrophysique de Bordeaux
D. Johnstone
National Research Council Canada
University of Victoria
J. K. Jorgensen
Köpenhamns universitet
M. Kaufman
San Jose State University
L. Kristensen
Universiteit Leiden
B. Larsson
Stockholms universitet
D. Lis
California Institute of Technology (Caltech)
M. Marseille
Netherlands Institute for Space Research (SRON)
C. McCoey
University of Waterloo
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
Michael Olberg
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
B. Parise
Stockholms universitet
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 Astronómico Nacional (OAN)
P. Saraceno
Istituto di Fisica dello Spazio Interplanetario, Rome
R. Shipman
Netherlands Institute for Space Research (SRON)
T. A. van Kempen
Harvard-Smithsonian Center for Astrophysics
R. Visser
Universiteit Leiden
S. Viti
University College London (UCL)
Istituto di Fisica dello Spazio Interplanetario, Rome
S. F. Wampfler
Eidgenössische Technische Hochschule Zürich (ETH)
F. Wyrowski
Max-Planck-Gesellschaft
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
Rijksuniversiteit Groningen
U. A. Yildiz
Universiteit Leiden
B. Delforge
Ecole Normale Superieure (ENS)
Radboud Universiteit
J. Desbat
Laboratoire d'Astrophysique de Bordeaux
W. A. Hatch
University of Calgary
I. Peron
Radboud Universiteit
Ecole Normale Superieure (ENS)
Institut de Radioastronomie Millimétrique (IRAM)
R. Schieder
Universität zu Köln
J. A. Stern
University of Calgary
D. Teyssier
European Space Astronomy Centre (ESAC)
N. Whyborn
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 Article Number: L120 L120Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201014603