Bound to Happen? Long Period Capture of Comets and Impact Statistics
Session 65 -- SL-9 Impact, PLanets
Oral presentation, Tuesday, 10, 1995, 2:00pm - 3:30pm

## [65.01] Bound to Happen? Long Period Capture of Comets and Impact Statistics

D. M. Kary (UCSB), L. Dones (San Jose St.)

Comet P/Shoemaker-Levy 9 was unusual for at least three reasons: 1) It was the first time a comet has been seen shortly after tidal breakup by a planet. 2) It was the first comet observed while gravitationally bound to a planet. Indeed, it had been bound to Jupiter for a surprisingly long time (at least 20 years) before its discovery (P. Chodas, private communication 1994). 3) It was the first comet observed to hit a planet. This conjunction of firsts causes one to ask whether there is any correlation between them. In particular, were the comet's close approach and later impact with Jupiter more likely because it had been bound to the planet for a long time? In an attempt to answer this question, we have performed a series of numerical integrations in the restricted 4-body problem (Sun, Jupiter, Saturn, and a test particle in solar orbit). The test particles cover a wide range of heliocentric inclinations (up to 10\$^\circ\$) and eccentricities (up to 0.8). Preliminary results suggest that \$\sim\$ 1/3 of the short-period objects which hit Jupiter in our simulations do so while gravitationally bound to the planet; however, the vast majority of these bodies are captured for at most a few years. Nonetheless, an object which is bound to the planet for an extended period of time is more likely to impact and/or tidally break up than one which is only trapped for a short time.

This work is supported in part by NASA Planetary Geology and Geophysics Grant \# NAGW-2061 at UCSB and by RTOP 151-01-60-09 at NASA Ames.