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Session 72 - Comet Hale-Bopp.
Display session, Friday, January 09
There have recently been two bright comets which have given us an excellent opportunity to study cometary chemistry. We were able to monitor the bright and exceptionally active Comet Hale-Bopp (1995 O1) for almost two years, and C/Hyakutake (1996 B2) passed extremely close to earth, allowing us to observe the inner coma with high spatial resolution and minimal beam dilution for short-lived species.
Our program for both comets concentrated on millimeter-wave observations of sulfur bearing molecules in an effort to understand the total sulfur budget of the comet. Using the National Radio Astronomy Observatory 12-m telescope on Kitt Peak we observed H_2S, CS, and OCS. Additionally, in C/Hale-Bopp we monitored the long and short-term variations in these species, and observed H_2CS and SO as well. This was the first observation of H_2CS in any comet.
C/Hale-Bopp is the first comet in which so many sulfur species have been observed. Analysis of the abundances of these species in comparison to the total atomic sulfur observed in both comets should reveal whether or not we can now account for all of the primary sulfur sources in comets. Perhaps the most interesting question that these observations leave unanswered is why C/Hale-Bopp appears to contain so much more SO and SO_2 (as observed by others) than any other comet.
Program listing for Friday