Long-Term Dynamics and the Orbital Inclinations of the Classical Kuiper Belt Objects

Abstract

We numerically integrated the orbits of 1458 particles in the region of the classical Kuiper belt (41 AU ≤ a ≤ 47 AU) to explore the role of dynamical instabilities in sculpting the inclination distribution of the classical Kuiper belt objects (KBOs). We find that the selective removal of low-inclination objects by overlapping secular resonances (ν17 and ν18) acts to raise the mean inclination of the surviving population of particles over 4 billion yr of interactions with Jupiter, Saturn, Uranus, and Neptune, though these long-term dynamical effects do not themselves appear to explain the discovery of KBOs with inclinations near 30°. Our integrations also imply that after 3 billion yr of interaction with the massive planets, high-inclination KBOs more efficiently supply Neptune-encountering objects, the likely progenitors of short-period comets, Centaurs, and scattered KBOs. The secular resonances at low inclinations may indirectly cause this effect by weeding out objects unprotected by mean motion resonances during the first 3 billion yr.