Volume 440, Number 2, September III 2005
|Page(s)||L21 - L24|
|Published online||01 September 2005|
Letter to the Editor
Isotopic abundances of carbon and nitrogen in Jupiter-family and Oort Cloud comets
Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, 4000 Liège, Belgium e-mail: firstname.lastname@example.org
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
Accepted: 21 July 2005
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 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)
© ESO, 2005
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