We have obtained 8 - 13 mu m spectra of comet C/1995 01 Hale-Bopp on UT June 11-12, July 22 and August 5-7 1996 at R > 3.5 AU. The spectra were acquired with the Cornell Spectrocam-10 imaging spectrograph at the Palomar 5-m Hale Telescope and with the Aerospace BASS infrared array spectrograph at the NASA Infrared Telescope Facility. Strong silicate emission is present in all of the spectra, about 75% above a blackbody continuum. The shape of the feature is very similar to that seen in comet P/Halley, including a peak at 11.25 mu m most likely due to crystalline olivine. This is the first time that a strong silicate feature has been detected in a comet beyond 2 AU. The dust continuum temperatures derived from fitting a grey body near 8 and 13 mu m are 27% - 37% higher than a black body in equilibrium. The strong silicate feature and the warm temperatures indicate that small grains were abundant in the coma. This research was supported in part at JPL under contract with NASA.
AAS/Division for Planetary Sciences Meeting Abstracts #28
- Pub Date:
- September 1996