CARBON ISOTOPE FRACTIONATION AND DEPLETION IN TMC1

super(12)C/ super(13)C isotopologue abundance anomalies have long been predicted for gas-phase chemistry in molecules other than CO and have recently been observed in the Taurus molecular cloud (TMC) in several species hosting more than one carbon atom, i.e., CCH, CCS, CCCS, and HC sub(3)N. Here we...

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Bibliographic Details
Published in:The Astrophysical journal 2012-03, Vol.747 (1), p.1-9
Main Authors: LISZT, H. S, ZIURYS, L. M
Format: Article
Language:English
Subjects:
ABUNDANCE
AMMONIA
Anomalies
Astronomy
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Carbon
CARBON 12
CARBON 13
CARBON IONS
Carbon monoxide
Depletion
Earth, ocean, space
Emission
Exact sciences and technology
FRACTIONATION
Molecular clouds
NITRILES
NITROGEN
OXYGEN
Pools
SULFUR
TELESCOPES
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Summary:super(12)C/ super(13)C isotopologue abundance anomalies have long been predicted for gas-phase chemistry in molecules other than CO and have recently been observed in the Taurus molecular cloud (TMC) in several species hosting more than one carbon atom, i.e., CCH, CCS, CCCS, and HC sub(3)N. Here we work to ascertain whether these isotopologic anomalies actually result from the predicted depletion of the super(13)C+ ion in an oxygen-rich optically shielded dense gas, or from some other more particular mechanism or mechanisms. We observed [lambda]3mm emission from carbon-, sulfur-, and nitrogen-bearing isotopologues of HNC, CS, and H sub(2)CS at three positions in Taurus (TMC1, L1527, and the NH sub(3) peak) using the ARO 12 m telescope. We saw no evidence of super(12)C/ super(13)C anomalies in our observations. Although the pool of C+ is likely to be depleted in super(13)C, super(13)C is not depleted in the general pool of carbon outside CO, which probably exists mostly in the form of C super(0). The observed isotopologic abundance anomalies are peculiar to those species in which they are found.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/747/1/55