Detection of acetylene in the infrared spectrum of comet Hyakutake.
Comets are rich in volatile materials, of which roughly 80% (by number) are water molecules. Considerable progress is being made in identifying the other volatile species, the abundances of which should enable us to determine whether comets formed primarily from ice-covered interstellar grains, or from material that was chemically processed in the early solar nebula. Here we report the detection of acetylene (C2H2) in the infrared spectrum of comet C/1996 B2 (Hyakutake). The estimated abundance is 0.3-0.9%, relative to water, which is comparable to the predicted solid-phase abundance in cold interstellar clouds. This suggests that the volatiles in comet Hyakotake may have come from ice-covered interstellar grains, rather than material processed in the accretion disk out of which the Solar System formed.
Brooke
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Jet Propulsion Laboratory, Pasadena, California 91109, USA.
Tokunaga
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Weaver
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Crovisier
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J
Bockelée-Morvan
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Crisp
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D000114:Acetylene / Q000032:analysis*; D019443:Cosmic Dust; D005118:Extraterrestrial Environment; D019110:Meteoroids; D013055:Spectrophotometry, Infrared
D019443:Cosmic Dust; D000114:Acetylene