UPPER LIMITS OF SO AND SO2 IN COMETS

We have calculated synthetic spectra of SO and compared them with spectra of Comets I-A-A and P/Halley, in which Wallis and Krishna-Swamy claimed a tentative identification of SO. We found no evidence for the presence of SO in these spectra. The derived upper limits on the production rates of SO and SO2 in Comet I-A-A were found to be at least 50 times less than the S2 production rate. We also found that the SO and SO2 upper limits in Comets P/Halley, P/Encke, and Bradfield (1979X) were less than the S2 abundance, reported in Comet IRAS-Araki-Alcock. Our results contradict recent irradiation experiments, which produced abundant SO compared with S2 under most circumstances. This may suggest totally different models of the S2 producing mechanism in comets. © 1991.