EDP Sciences
Free access
Issue
A&A
Volume 440, Number 2, September III 2005
Page(s) L21 - L24
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500160


A&A 440, L21-L24 (2005)
DOI: 10.1051/0004-6361:200500160

Letter

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

D. Hutsemékers1, J. Manfroid1, E. Jehin2, C. Arpigny1, A. Cochran3, R. Schulz4, J. A. Stüwe5 and J.-M. Zucconi6

1  Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, 4000 Liège, Belgium
    e-mail: hutsemekers@astro.ulg.ac.be
2  European Southern Observatory, Casilla 19001, Santiago, Chile
3  Department of Astronomy and McDonald Observatory, University of Texas at Austin, C-1400, Austin, USA
4  ESA/RSSD, ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands
5  Leiden Observatory, 2300 RA Leiden, The Netherlands
6  Observatoire de Besançon, 25010 Besançon Cedex, France

(Received 8 June 2005 / Accepted 21 July 2005 )

Abstract
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 $\simeq$ 90 and 14N/15N $\simeq145$ 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.


Key words: comets: abundances -- comets: individual: 88P/Howell -- comets: individual: C/1999 S4 (LINEAR)

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