C.D.S. - SIMBAD4 rel 1.7 - 2021.04.21CEST13:37:33

2008A&A...479..493A - Astronomy and Astrophysics, volume 479, 493-501 (2008/2-4)

Detection of circumstellar CH2CHCN, CH2CN, CH3CCH, and H2CS.


Abstract (from CDS):

We report on the detection of vinyl cyanide (CH2CHCN), cyanomethyl radical (CH2CN), methylacetylene (CH3CCH), and thioformaldehyde (H2CS) in the C-rich star IRC +10216. These species, which are all known to exist in dark clouds, were detected for the first time in the circumstellar envelope around an AGB star. The four molecules were detected through pure rotational transitions in the course of a λ 3mm line survey carried out with the IRAM 30-m telescope. The molecular column densities were derived by constructing rotational temperature diagrams. A detailed chemical model of the circumstellar envelope is used to analyze the formation of these molecular species. We have found column densities in the range 5x1012-2x1013cm2, which translates to fractional abundances relative to H2 of several 10–9. The chemical model is reasonably successful in explaining the derived abundances through gas phase synthesis in the cold outer envelope. We also find that some of these molecules, CH2CHCN and CH2CN, are most probably excited through infrared pumping to excited vibrational states. The detection of these species stresses the similarity between the molecular content of cold dark clouds and C-rich circumstellar envelopes. However, some differences in the chemistry are indicated by partially saturated carbon chains being present in IRC +10216 at a lower level than those that are highly unsaturated, while in TMC-1 both types of species have comparable abundances.

Abstract Copyright:

Journal keyword(s): astrochemistry - stars: circumstellar matter - stars: AGB and post-AGB - stars: carbon - stars: individual: IRC +10216

Simbad objects: 5

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Number of rows : 5

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1412 0
2 RAFGL 618 pA* 04 42 53.6245215366 +36 06 53.397219192   16.32   12.59   C-rich 964 0
3 QSO J0854+2006 BLL 08 54 48.8749311881 +20 06 30.642936668   15.91 15.43 15.56   ~ 2074 1
4 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2187 0
5 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1996 1

    Equat.    Gal    SGal    Ecl

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