Palomar observations of the R impact of comet Shoemaker‐Levy 9: II. Spectra

Abstract

We present mid‐infrared spectroscopic observations from Palomar observatory of the impact of fragment R of comet P/Shoemaker‐Levy 9 with Jupiter on 21 July 1994. Low‐resolution 8–13 µ m spectra taken near the peak of the lightcurve show a broad emission feature that resembles the silicate feature commonly seen in comets and the interstellar medium. We use this feature to estimate the dust content of the impact plume. The overall infrared spectral energy distribution at the time of peak brightness is consistent with emission from an optically‐thin layer of small particles at ∼600 K. Integrating over the spectrum and the lightcurve, we obtain a total radiated energy from the R impact of ≥ 2 × 10 25 ergs and a plume mass of ≥ 3 × 10 13 g.