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| Paper: |
On the Dynamical Lifetimes of Planet--Crossing Objects |
| Volume: |
107, Completing the Inventory of the Solar System |
| Page: |
233 |
| Authors: |
Dones, L.; Levison, H. F.; Duncan, M. |
| Abstract: |
We have carried out orbital integrations of many test particles with initial orbits similar to those of four Centaurs (Chiron, Pholus, 1993 HA$_2$, and 1994 TA) and two distant Jupiter-family comets (Schwassmann-Wachmann 1 (S-W 1) and Oterma). Our integrations include the mutual interactions of the four giant planets, and were performed for times up to 50 Myr. The median dynamical lifetime tmed ranges from 0.5 Myr for S-W 1 to 5 Myr for 1993 HA$_2$. The usual fate of each object is ejection from the solar system. At early times ($t < tmed), the population of each object decays exponentially. At times of order 2--20 tmed, the populations decline more slowly, so that the fraction of survivors is roughly tmed/t. Many late survivors evolve to orbits with larger perihelia, which typically suffer smaller planetary perturbations. We compare our results with the predictions of a cometary diffusion equation and a Monte Carlo, Öpik-type code. The diffusion equation overestimates the number of survivors at early times and underestimates the survivors at late times; the Öpik code generally overestimates the survivors at all times. The discrepancy between the integrations and the Öpik code probably arises because close encounters between small bodies and planets tend to be clustered in time. |
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