Paper: astro-ph/0508033
Date: Mon, 1 Aug 2005 10:36:38 GMT (15kb)

Title: Isotopic abundances of carbon and nitrogen in Jupiter-family and Oort
Cloud comets

Authors: D. Hutsemekers, J. Manfroid, E. Jehin, C. Arpigny, A. Cochran, R.
Schulz, J.A. Stuwe, J.-M. Zucconi

Comments: Accepted for publication in A&A letters
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The 12C14N/12C15N and 12C14N/13C14N isotopic ratios are determined for the
first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically
peculiar Oort Cloud comet C/1999 S4 (LINEAR). By comparing these measurements
to previous ones derived for six other Oort Cloud comets (including one of
Halley-type), we find that both the carbon and nitrogen isotopic ratios are
constant within the uncertainties. The mean values are 12C/13C ~ 90 and 14N/15N
\~ 145 for the eight comets. These results strengthen the view that CN radicals
originate from refractory organics formed in the protosolar molecular cloud and
subsequently incorporated in comets.

\\ ( http://arXiv.org/abs/astro-ph/0508033 , 15kb)