Detection of C2H in cold dark clouds
| Autor: | Alwyn Wootten, R. B. Loren, Ronald L. Snell, E. P. Bozyan, D. B. Garrett |
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| Rok vydání: | 1980 |
| Předmět: | |
| Zdroj: | The Astrophysical Journal. 239:844 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/158168 |
| Popis: | We have surveyed a wide variety of interstellar clouds for the radical C/sub 2/H including a number of cold dust clouds in which star formation is not known to be occurring (yet). We have also examined small dust clouds with single infrared sources or Herbig-Haro objects. Definite detections of C/sub 2/H were made in 19 of the 30 regions examined with a further 3 possible detections. C/sub 2/H was detected in 8 cold dust clouds. We have made extensive maps of the unusual dust cloud L1534 (TMC 1) and of the M17SW star-formation region. Smaller maps of B227, L43, and L134N were also made. The L1534 and M17SW maps show that the C/sub 2/H distribution is well correlated with that of other molecular species in these clouds. The fractional abundance of C/sub 2/H in cold clouds is typically found to be X(C/sub 2/H)approx. =6 x 10/sup -9/. The molecule HC/sub 3/N is thought to have the same chemical precursor, C/sub 2/H/sub 2//sup +/, as the C/sub 2/H molecule. The ratio of abundances X(C/sub 2/H)/X(HC/sub 3/N) tests the chemical formation path, and it falls in the range of 3--10, consistent with the ratio expected from gas phase molecule formation models. Theremore » is no evidence, however, for a greater abundance decrease of X(C/sub 2/H) with increasing density than for other molecular species in any of the clouds we have examined.« less |
| Databáze: | OpenAIRE |
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