A high resolution line survey of IRC 10216 with Herschel. First results: Detection of warm silicon dicarbide SiC2 - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: We present the first results of a high-spectral-resolution survey of thecarbon-rich evolved star IRC+10216 that was carried out with the HIFIspectrometer onboard Herschel. This survey covers all HIFI bands, with aspectral range from 488 to 1901GHz. In this letter we focus on the band-1bspectrum, in a spectral range 554.5-636.5GHz, where we identified 130 spectralfeatures with intensities above 0.03 K and a signal-to-noise ratio >5. Detectedlines arise from HCN, SiO, SiS, CS, CO, metal-bearing species and,surprisingly, silicon dicarbide SiC2. We identified 55 SiC2 transitionsinvolving energy levels between 300 and 900 K. By analysing these rotationallines, we conclude that SiC2 is produced in the inner dust formation zone, withan abundance of ~2x10^-7 relative to molecular hydrogen. These SiC2 lines havebeen observed for the first time in space and have been used to derive an SiC2rotational temperature of ~204 K and a source-averaged column density of~6.4x10^15 cm^-2. Furthermore, the high quality of the HIFI data set was usedto improve the spectroscopic rotational constants of SiC2.



Autor: J. Cernicharo, L.B.F.M. Waters, L. Decin, P. Encrenaz, A.G.G.M. Tielens, M. Agundez, E. De Beck, H.S.P. Muller, J.R. Goicoechea,

Fuente: https://arxiv.org/







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