Simple Model for the Light Curve Generated by a Shoemaker-Levy 9 Impact

摘要

The impact of a typical Shoemaker-Levy 9 fragment produced three light peaks as seen from Earth. By contrast, Galileo, which had a direct view of the impacts, saw two peaks, one at entry, and one at plumefall. In this paper, we present a simple, highly idealized model of a ballistic plume, which we then use to fit the observed light curve of the R impact as recorded at Mauna Kea and Mount Palomar. From the light curve, we find that the nominal R fragment had diameter 450-500 m and mass approx. 2-3 x 10 to the 13th power g. The uncertainty in the mass is probably about a factor of 3, with a smaller event more likely than a larger one.