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: individual objects: SgrB2(M)

ISM: kinematics and dynamics

ISM:

cologne database

facility

cdms

molecular-spectroscopy

outflow

star-formation

ISM: structure

stars: formation

submillimeter: ISM

molecules

b2

Författare

R. Rolffs

Max Planck-institutet

Universität zu Köln

P. Schilke

Max Planck-institutet

Universität zu Köln

C. Comito

Max Planck-institutet

E. A. Bergin

University of Michigan

F. F. S. van der Tak

Netherlands Institute for Space Research (SRON)

D. C. Lis

CalTech

S. L. Qin

Universität zu Köln

K. M. Menten

Max Planck-institutet

R. Güsten

Max Planck-institutet

T. A. Bell

CalTech

G. A. Blake

Caltech Division of Geological and Planetary Sciences

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

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

Centro de Astrobiologia (CAB)

M. L. Dubernet

Universite Pierre et Marie Curie (UPMC)

GEPI - Galaxies, Etoiles, Physique, Instrumentation

M. Emprechtinger

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

Institut National des Sciences de l'Univers

Université de Toulouse

D. Johnstone

National Research Council Canada

W. D. Langer

Jet Propulsion Laboratory, California Institute of Technology

W. D. Latter

CalTech

S. D. Lord

CalTech

S. Maret

Laboratoire d'Astrophysique de l'Observatoire de Grenoble

P. G. Martin

Canadian Institute for Theoretical Astrophysics

G. J. Melnick

Harvard-Smithsonian Center for Astrophysics

P. Morris

CalTech

Holger Muller

Universität zu Köln

J. A. Murphy

Maynooth University

V. Ossenkopf

Universität zu Köln

Netherlands Institute for Space Research (SRON)

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

CalTech

R. Plume

University of Calgary

S. Schlemmer

Universität zu Köln

J. Stutzki

Universität zu Köln

N. Trappe

Maynooth University

C. Vastel

Institut National des Sciences de l'Univers

Université de Toulouse

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

CalTech

M. C. Diez-Gonzalez

Centro Astronomico de Yebes

R. Bachiller

Centro Astronomico de Yebes

J. Martin-Pintado

CSIC - Instituto de Estructura de la Materia (IEM)

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 Article Number: L46 - L46

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201015106