HR: 1340h
AN: P53A-1462    [Abstracts]
TI: Collision, Rotation, and Accretion of Particles in Planetary Rings
AU: * Ohtsuki, K
EM: ohtsuki@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 392 UCB, Boulder, CO 80309-0392 United States
AB: Collisions between particles play an essential role in dynamical evolution of planetary rings: they result in either rebound, accretion, or fragmentation of particles, and cause angular momentum transport in rings. Furthermore, oblique impacts between particles with rough surfaces lead to rotation. Recent works have shown that small moonlets embedded in planetary rings would spin slowly in the prograde direction when impacting particles are much smaller than the moonlets. In this case, the rotation of a moonlet is determined by the mean angular momentum brought by a number of small impacts. However, when the mass of impacting particles is comparable to the moonlet's mass, dispersions in the rotation rates become significant. This random component of rotation needs to be taken into account in the case of rotation of ring particles. We have derived an equation which describes the evolution of the dispersion of rotation rates of ring particles, and obtained the rate of evolution using three-body orbital integration. Using these results and N-body simulation, we will discuss rotation of ring particles and moonlets. We also obtained gravitational capture probability of colliding particles using three-body orbital integration, which takes into account velocity distribution and surface friction of particles. On the basis of our numerical results, we will also discuss accretional evolution of ring particles.
DE: 6265 Planetary rings
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting