The Jovian stratosphere after comet Shoemaker-Levy/9: Unusual isotopic ratios in molecular trace constituents

Since the collision of comet Shoemaker-Levy/9 with Jupiter in 1994 July, a number of minor molecular species have been observed to persist in the stratosphere of the planet. Here we report observations acquired in 1998 September at frequencies near 350 GHz ( wavelength 850 mum) of HCN and CS and their respective isotopomers H(13)CN, HC(15)N, and C(34)S. Through radiative transfer modeling of the observed lines, we find that the isotopic abundance ratios (12)C/(13)C, (14)N/(15)N, and (32)S/(34)S are considerably elevated with respect to their terrestrial values. We speculate that this result indicates an unusual composition for comet Shoemaker-Levy/9, or that cometary grains evaporated in the collisions significantly modified the isotope ratios.