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L.M. Woodney (Lowell Observatory), M.F. A'Hearn (Univ. of Maryland), R. Meier (Gretag Imaging)
Previous to the apparitions of Hyakutake (C/1996 B2) and Hale-Bopp (C/1995 O1), it was clear that not all of the sulfur parent molecules were accounted for in comets. Four new sulfur bearing species were discovered in these comets (OCS, SO, SO2 and H2CS) making it likely that we have now found all of the major sulfur parent species. However, it is possible that other species such as CH3SH are present in small amounts. We will present results from Monte Carlo modeling of the sulfur budget in Hale-Bopp and discuss the completeness of the sulfur inventory of the nucleus as well as comparisons of cometary abundances to ISM abundances.
Additionally, our monitoring of the production rates of OCS, CS and H2S with the National Radio Astronomy Observatory 12-m telescope revealed that the production rate of OCS had a very different dependence on heliocentric distance than that of the other species: r-4 instead of r-2. This could imply that there is some radial differentiation in at least the outer layers of the nucleus, or that OCS has an extended source.
This research was supported by NASA's Planetary Astronomy and GSRP programs.