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

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 ~ 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.

arXiv commentAccepted for publication in A&A letters

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• Observations of nitrogen isotope fractionation in deeply embedded protostars
• New constraints on the delivery of cometary water and nitrogen to Earth from the 15N/14N isotopic ratio
• Cometary diversity and cometary families
• A Bima Array Survey of Molecules in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)
• Nitrogen Atmospheres of the Icy Bodies in the Solar System
• Late Delivery of Nitrogen to Earth