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A search for HCCN in molecular cloudsWe have conducted a deep search for HCCN towards the dark cloud TMC-l and several GMC's via its N(J) = 1(2)-->0(1) transition. HCCN was not detected in any of these sources. Towards TMC-l, assuming optically thin emission, the total column density upper limit is NHCCN < or = 2 x 10(12) cm-2, which corresponds to a fractional abundance upper limit with respect to molecular hydrogen of fHCCN < or = 2 x 10(-10). We find the abundance ratio of HCN:HCCN:HCCCN in TMC-l to be l : <0.01 : 0.3, which suggests that carbon-chain growth by the addition of single carbon atoms may not be efficient under dark cloud conditions. The HCCN abundance limit also places constraints on the branching ratio for the products of the dissociative electron recombination H3C2N+ + e.
Document ID
20040089664
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
McGonagle, D.
(Five College Radio Astronomy Observatory Amherst, MA 01003, United States)
Irvine, W. M.
Date Acquired
August 21, 2013
Publication Date
June 1, 1996
Publication Information
Publication: Astronomy and astrophysics
Volume: 310
Issue: 3
ISSN: 0004-6361
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: AST-9115721
CONTRACT_GRANT: NAGW-436
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

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