Understanding the chemical complexity in Circumstellar Envelopes of C-Rich AGB stars: the case of IRC +10216

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• 作者：M. Agúndez ; J. Cernicharo ; J. R. Pardo ; J. P. Fonfría?Expósito ; M. Guélin ; E. D. Tenenbaum ; L. M. Ziurys and A. J. Apponi
• 关键词：Astrochemistry ; Circumstellar matter ; Molecular processes ; AGB stars ; IRC +10216
• 刊名：Astrophysics and Space Science
• 出版年：2008
• 出版时间：January, 2008
• 年：2008
• 卷：313
• 期：1-3
• 页码：229-233
• 全文大小：387.7 KB
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics
  Astronomy
  
• 出版者：Springer Netherlands
• ISSN：1572-946X

文摘

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.