Abstract
view Abstract Citations (2) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of C 3N in the Spiral Arm Gas Clouds in the Direction of Cassiopeia A Bell, M. B. ; Matthews, H. E. Abstract We report detection of the strongest component of the N = 1-0 transition of the free radical C3N in absorption against Cas A. The inferred column densities are NL(C3N) = 1012 -1013/sq cm depending on whether the absorbing molecules are in the low-density interstellar medium or in denser molecular gas (cloudlets) in the orion and Perseus arms. After considering both cases and comparing the results to published abundances in TMC-1 we find no clear evidence that either C3N or C4H are located in diffuse gas and conclude that both are more likely located in dense gas clouds. Our results do suggest, at least in the direction of Cas A, that the C(n)H chains, like the C(n)N chains, may be sufficiently abundant for the longer members to be carriers of the diffuse interstellar bands (DIBs) if they can survive in unprotected regions. Unlike the case for C4H, however, where the absorption line is relatively strong in the Orion arm gas, there is evidence in the C3N case for stronger absorption in the Perseus arm. We suggest that this abundance difference between the two arms might be related to the fact that different families of DIBs have been reported whose relative abundance also varies from source to source. Publication: The Astrophysical Journal Pub Date: January 1995 DOI: 10.1086/175066 Bibcode: 1995ApJ...438..223B Keywords: Absorption Spectra; Abundance; Carbon Compounds; Cassiopeia A; Milky Way Galaxy; Molecular Gases; Interstellar Gas; Molecular Clouds; Astrophysics; ISM: ABUNDANCES; ISM: MOLECULES; RADIO LINES: ISM full text sources ADS | data products SIMBAD (3)
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