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A high-resolution line survey of IRC+10216 with Herschel/HIFI First results: Detection of warm silicon dicarbide (SiC2)

J. Cernicharo ; Lbfm Waters ; L. Decin ; P. Encrenaz ; Aggm Tielens ; M. Agundez ; E. De Beck ; H. S. P. Muller ; J. R. Goicoechea ; M. J. Barlow ; A. Benz ; N. Crimier ; F. Daniel ; A. M. di Giorgio ; M. Fich ; T. Gaier ; P. Garcia-Lario ; A. de Koter ; T. Khouri ; René Liseau (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; R. Lombaert ; N. Erickson ; J. R. Pardo ; J. C. Pearson ; R. Shipman ; C. S. Contreras ; D. Teyssier
Astronomy and Astrophysics (0004-6361). Vol. 521 (2010), p. Article Number: L8.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: stars: individual: IRC+10216, stars: carbon, stars: AGB and post-AGB, line: identification, astrochemistry, submillimeter hcn laser, dust formation zone, molecular-spectroscopy, laboratory measurement, bure observations, cologne database, envelope, chemistry, emission, identification



Denna post skapades 2010-12-17. Senast ändrad 2015-07-10.
CPL Pubid: 131190

 

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Institutioner (Chalmers)

Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik (2010-2017)

Ämnesområden

Astronomi, astrofysik och kosmologi

Chalmers infrastruktur