Dynamical stability in the outer solar system and the delivery of short period comets

Abstract

A survey is presented of test particle stability in the outer solar system. Test particles are numerically integrated for durations ranging from 20 to 800 million yr. No evidence is found that Saturn, Uranus, and Neptune cannot retain Trojan-like asteroids on time scales of 20 million yr. Test particles placed on orbits near Saturn's Lagrange L(4) and L(5) points experience close encounters with planets on short time scales, but test particles further from the Lagrange points remain for the full integration. Most test particles in the Saturn-Uranus and Uranus-Neptune regions are removed in 10 million yr, excluding small regions between Uranus and Neptune in which a few test particles endure the full 800 million yr integration. Test particles on initially circular orbits between Jupiter and Saturn are removed by close encounters with the planets on time scales of 10 exp 4 to 10 exp 5 yr. The above mentioned results provide an insight concerning the hypothesized Kuiper belt of comets, whose mass estimate is given.