Understanding the chemical complexity in Circumstellar Envelopes of C-Rich AGB stars: the case of IRC +10216 |
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| Authors: | M Agúndez J Cernicharo J R Pardo J P Fonfría Expósito M Guélin E D Tenenbaum L M Ziurys A J Apponi |
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| Institution: | (1) Departamento de Astrofísica Molecular e Infrarroja, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain;(2) Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 St. Martin d’Heres, France;(3) Departments of Chemistry and Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA |
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| Abstract: | The circumstellar envelopes of carbon-rich AGB stars show a chemical complexity that is exemplified by the prototypical object
IRC +10216, in which about 60 different molecules have been detected to date. Most of these species are carbon chains of the
type C
n
H, C
n
H2, C
n
N, HC
n
N. We present the detection of new species (CH2CHCN, CH2CN, H2CS, CH3CCH and C3O) achieved thanks to the systematic observation of the full 3 mm window with the IRAM 30m telescope plus some ARO 12m observations.
All these species, known to exist in the interstellar medium, are detected for the first time in a circumstellar envelope
around an AGB star. These five molecules are most likely formed in the outer expanding envelope rather than in the stellar
photosphere. A pure gas phase chemical model of the circumstellar envelope is reasonably successful in explaining the derived
abundances, and additionally allows to elucidate the chemical formation routes and to predict the spatial distribution of
the detected species. |
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| Keywords: | Astrochemistry Circumstellar matter Molecular processes AGB stars IRC +10216 |
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