Excitation and abundance of C3 in star forming cores Herschel/HIFI observations of the sight-lines to W31C and W49N
Journal article, 2010
We present spectrally resolved observations of triatomic carbon (C-3) in several ro-vibrational transitions between the vibrational ground state and the low-energy nu(2) bending mode at frequencies between 1654-1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C-3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C-3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (T-rot) of similar to 50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived T-rot, we get column densities N(C-3) similar to 7-9 x 10(14) cm(-2) and abundance x(C-3) similar to 10(-8) with respect to H-2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C-3) = 10(-8), T-kin = 30-50 K, N(C-3) = 1.5 x 10(15) cm(-2) fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis.
irc+10216
dust
ISM: lines and bands
spectroscopy
ISM:
ISM: molecules
hii-regions
g10.6-0.4
h-ii-regions
spiral-arm clouds
individual objects: W49N
radiative transfer
absorption
interstellar c-3
translucent
ISM: individual objects: W31C
Author
B. Mookerjea
Tata Institute of Fundamental Research
T. Giesen
University of Cologne
J. Stutzki
University of Cologne
J. Cernicharo
Centro de Astrobiologia (CAB)
J. R. Goicoechea
Centro de Astrobiologia (CAB)
M. de Luca
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. A. Bell
California Institute of Technology (Caltech)
H. Gupta
Jet Propulsion Laboratory, California Institute of Technology
M. Gerin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Carina Persson
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
P. Sonnentrucker
Johns Hopkins University
Z. Makai
University of Cologne
John H Black
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
F. Boulanger
Institut d'Astrophysique Spatiale
A. Coutens
University of Toulouse
E. Dartois
Institut d'Astrophysique Spatiale
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
E. Falgarone
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. R. Geballe
Gemini Observatory North
B. Godard
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
P. F. Goldsmith
Jet Propulsion Laboratory, California Institute of Technology
C. Gry
Laboratoire d'Astrophysique de Marseille
P. Hennebelle
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
E. Herbst
Ohio State University
P. Hily-Blant
Laboratoire d'Astrophysique de Grenoble
C. Joblin
University of Toulouse
M. Kazmierczak
Nicolaus Copernicus University
R. Kolos
Polish Academy of Sciences
J. Krelowski
Nicolaus Copernicus University
D. C. Lis
California Institute of Technology (Caltech)
J. Martin-Pintado
Centro de Astrobiologia (CAB)
K. M. Menten
Max Planck Society
Raquel Monje
California Institute of Technology (Caltech)
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
M. Salez
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
S. Schlemmer
University of Cologne
M. Schmidt
Polish Academy of Sciences
D. Teyssier
European Space Astronomy Centre (ESAC)
C. Vastel
University of Toulouse
S. Yu
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
P. Dieleman
Netherlands Institute for Space Research (SRON)
R. Güsten
Max Planck Society
C. E. Honingh
University of Cologne
P. Morris
California Institute of Technology (Caltech)
P. Roelfsema
Netherlands Institute for Space Research (SRON)
R. Schieder
University of Cologne
Aggm Tielens
Leiden University
J. Zmuidzinas
California Institute of Technology (Caltech)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L13 - L13Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201015095