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[16.11] Nuclear spin temperatures of water, ammonia and methane in comet C/2001 Q4 (NEAT)

H. Kawakita (Kyoto Sangyo University), N. Dello Russo (Johns Hopkins University), R. Furusho (Waseda University), T. Fuse (Subaru telescope, National Astronomical Observatory of Japan), J. Watanabe (National Astronomical Observatory of Japan), D. Boice (Southwest Reseach Institute), N. Arimoto (National Astronomical Observatory of Japan), K. Sadakane (Osaka Kyoiku University), M. Ohkubo (Kyoto University), K. Ohnishi (Nagoya Science Museum)

The real meaning of cold nuclear spin temperatures found in cometary molecules is still puzzling. Usually the nuclear spin temperature has been considered to be the physical temperature where the molecules formed (or condensed) on cold grains in thermal equilibrium. If so, the nuclear spin temperatures of different molecular species should be the same. Here we report the nuclear spin temperatures of water, ammonia and methane in comet C/2001 Q4 (NEAT) and discuss the existence of such thermal equilibrium process. Those nuclear spin temperatures are consistent with one another, indicating ~ 30 K. Our results support the hypothesis that the nuclear spin temperature was determined in thermal equilibrium, namely, the nuclear spin temperature can be used to infer the physical temperature.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.