Reversal of infall in SgrB2(M) revealed by Herschel/HIFI observations of HCN lines at THz frequencies
Artikel i vetenskaplig tidskrift, 2010
Aims. To investigate the accretion and feedback processes in massive star formation, we analyze the shapes of emission lines from hot molecular cores, whose asymmetries trace infall and expansion motions. Methods. The high-mass star forming region SgrB2(M) was observed with Herschel/HIFI (HEXOS key project) in various lines of HCN and its isotopologues, complemented by APEX data. The observations are compared to spherically symmetric, centrally heated models with density power-law gradient and different velocity fields (infall or infall+expansion), using the radiative transfer code RATRAN. Results. The HCN line profiles are asymmetric, with the emission peak shifting from blue to red with increasing J and decreasing line opacity (HCN to (HCN)-C-13). This is most evident in the HCN 12-11 line at 1062 GHz. These line shapes are reproduced by a model whose velocity field changes from infall in the outer part to expansion in the inner part. Conclusions. The qualitative reproduction of the HCN lines suggests that infall dominates in the colder, outer regions, but expansion dominates in the warmer, inner regions. We are thus witnessing the onset of feedback in massive star formation, starting to reverse the infall and finally disrupting the whole molecular cloud. To obtain our result, the THz lines uniquely covered by HIFI were critically important.
ISM: kinematics and dynamics
submillimeter: ISM
ISM: individual objects: SgrB2(M)
molecules
b2
ISM: structure
cdms
molecular-spectroscopy
stars: formation
cologne database
star-formation
facility
ISM:
outflow
Författare
R. Rolffs
Max-Planck-Gesellschaft
Universität zu Köln
P. Schilke
Max-Planck-Gesellschaft
Universität zu Köln
C. Comito
Max-Planck-Gesellschaft
E. A. Bergin
University of Michigan
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
D. C. Lis
California Institute of Technology (Caltech)
S. L. Qin
Universität zu Köln
K. M. Menten
Max-Planck-Gesellschaft
R. Güsten
Max-Planck-Gesellschaft
T. A. Bell
California Institute of Technology (Caltech)
G. A. Blake
California Institute of Technology (Caltech)
E. Caux
Institut National des Sciences de l'Univers
Université de Toulouse
C. Ceccarelli
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
J. Cernicharo
Centro de Astrobiologia (CAB)
N. R. Crockett
University of Michigan
F. Daniel
Centro de Astrobiologia (CAB)
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. L. Dubernet
Université Pierre et Marie Curie (UPMC)
Observatoire de Paris-Meudon
M. Emprechtinger
California Institute of Technology (Caltech)
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. Gerin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. F. Giesen
Universität zu Köln
J. R. Goicoechea
Centro de Astrobiologia (CAB)
P. F. Goldsmith
Jet Propulsion Laboratory, California Institute of Technology
H. Gupta
Jet Propulsion Laboratory, California Institute of Technology
E. Herbst
Ohio State University
C. Joblin
Université de Toulouse
Institut National des Sciences de l'Univers
D. Johnstone
National Research Council Canada
W. D. Langer
Jet Propulsion Laboratory, California Institute of Technology
W. D. Latter
California Institute of Technology (Caltech)
S. D. Lord
California Institute of Technology (Caltech)
S. Maret
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
P. G. Martin
Institut canadien d'astrophysique théorique
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
P. Morris
California Institute of Technology (Caltech)
Holger Muller
Universität zu Köln
J. A. Murphy
Maynooth University
V. Ossenkopf
Netherlands Institute for Space Research (SRON)
Universität zu Köln
J. C. Pearson
Jet Propulsion Laboratory, California Institute of Technology
M. Perault
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. G. Phillips
California Institute of Technology (Caltech)
R. Plume
University of Calgary
S. Schlemmer
Universität zu Köln
J. Stutzki
Universität zu Köln
N. Trappe
Maynooth University
C. Vastel
Université de Toulouse
Institut National des Sciences de l'Univers
S. Wang
University of Michigan
H. W. Yorke
Jet Propulsion Laboratory, California Institute of Technology
S. Yu
Jet Propulsion Laboratory, California Institute of Technology
J. Zmuidzinas
California Institute of Technology (Caltech)
M. C. Diez-Gonzalez
Observatorio de Yebes (IGN)
R. Bachiller
Observatorio de Yebes (IGN)
J. Martin-Pintado
Consejo Superior de Investigaciones Científicas (CSIC)
W. Baechtold
Eidgenössische Technische Hochschule Zürich (ETH)
Michael Olberg
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
L. H. Nordh
Stockholms universitet
John Gill
Jet Propulsion Laboratory, California Institute of Technology
Goutam Chattopadhyay
Jet Propulsion Laboratory, California Institute of Technology
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L46 - L46Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201015106