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[38.06] Relationship Between Spin Temperatures and Chemical Compositions in Comets

H. Kawakita (Gunma Astronomical Observatory), J.-I. Watanabe, R. Furusho, T. Fuse (National Astronomical Observatory of Japan)

Ortho-to-para ratios (OPRs) of cometary molecules are considered to be one of primordial characters in comets. The OPRs of cometary water and ammonia were derived in several comets so far, and the nuclear spin temperatures corresponding to the observed OPRs concentrate in 30±5 K. It appears that the spin temperature could reflect the physical temperature of dust grains where the molecule formed. If this hypothesis is right and the chemical composition has been unchanged after the ice formation, the correlation between the spin temperature and the chemical composition could be found. We discuss on the relationship between the spin temperatures and the ammonia to water abundance ratios in comets.

This work was financially supported by the Ministry of Education, Science, and Culture of Japan under Grant No. 15740127 (H. Kawakita).

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.