A high-resolution line survey of IRC+10216 with Herschel/HIFI First results: Detection of warm silicon dicarbide (SiC2)
Journal article, 2010
We present the first results of a high-spectral-resolution survey of the carbon-rich evolved star IRC+10216 that was carried out with the HIFI spectrometer onboard Herschel. This survey covers all HIFI bands, with a spectral range from 488 to 1901 GHz. In this letter we focus on the band-1b spectrum, in a spectral range 554.5-636.5 GHz, where we identified 130 spectral features with intensities above 0.03 K and a signal-to-noise ratio >5. Detected lines arise from HCN, SiO, SiS, CS, CO, metal-bearing species and, surprisingly, silicon dicarbide (SiC2). We identified 55 SiC2 transitions involving energy levels between 300 and 900 K. By analysing these rotational lines, we conclude that SiC2 is produced in the inner dust formation zone, with an abundance of similar to 2 x 10(-7) relative to molecular hydrogen. These SiC2 lines have been observed for the first time in space and have been used to derive an SiC2 rotational temperature of similar to 204 K and a source-averaged column density of similar to 6.4 x 10(15) cm(-2). Furthermore, the high quality of the HIFI data set was used to improve the spectroscopic rotational constants of SiC2.
molecular-spectroscopy
stars: individual: IRC+10216
emission
dust formation zone
astrochemistry
identification
laboratory measurement
envelope
line: identification
stars: carbon
chemistry
cologne database
bure observations
submillimeter hcn laser
stars: AGB and post-AGB
Author
J. Cernicharo
Centro de Astrobiologia (CAB)
Lbfm Waters
KU Leuven
Anton Pannekoek Institute for Astronomy
L. Decin
KU Leuven
Anton Pannekoek Institute for Astronomy
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Aggm Tielens
Leiden University
M. Agundez
Observatoire de Paris-Meudon
Centro de Astrobiologia (CAB)
Elvire De Beck
KU Leuven
Holger Muller
University of Cologne
J. R. Goicoechea
Centro de Astrobiologia (CAB)
M. J. Barlow
University College London (UCL)
A. Benz
Swiss Federal Institute of Technology in Zürich (ETH)
N. Crimier
Centro de Astrobiologia (CAB)
F. Daniel
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Centro de Astrobiologia (CAB)
A. M. di Giorgio
University of Rome Tor Vergata
M. Fich
University of Waterloo
T. Gaier
California Institute of Technology (Caltech)
P. Garcia-Lario
European Space Agency (ESA)
A. de Koter
Anton Pannekoek Institute for Astronomy
Sterrekundig Instituut Utrecht
T. Khouri
Anton Pannekoek Institute for Astronomy
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
R. Lombaert
KU Leuven
N. Erickson
University of Massachusetts
J. R. Pardo
Centro de Astrobiologia (CAB)
J. C. Pearson
California Institute of Technology (Caltech)
R. Shipman
Netherlands Institute for Space Research (SRON)
C. S. Contreras
Centro de Astrobiologia (CAB)
D. Teyssier
European Space Agency (ESA)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L8- L8Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201015150