HR: 1340h
AN: P33B-0249    [Abstracts]
TI: Collisional and Rotational Evolution of Planetary Rings
AU: * Ohtsuki, K
EM: ohtsuki@lasp.colorado.edu
AF: LASP, Univ. of Colorado, 392 UCB, Boulder, CO 80309-0392 United States
AB: Collisions between particles play an essential role in dynamical evolution of planetary rings. Inelastic collisions between particles 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. We derived an evolution equation for rotational energy of ring particles with an arbitrary size distribution; solving this equation and the evolution equation for random velocities simultaneously, we obtained equilibrium rotation rates of particles (Ohtsuki 2005, Astrophys. J. 626, L61). We found that 10cm-sized or smaller particles spin more than several tens to one hundred times in one orbital period, while large particles spin slowly. Also, our N-body simulation showed that the spin axes of slowly rotating large particles have a tendency to be nearly aligned in the direction normal to the ring plane, while rapidly rotating small particles have random spin orientation (Ohtsuki and Toyama 2005, Astron. J. 130, 1302). These rotational properties of ring particles need to be taken into account in modeling their thermal emission. We will also discuss effects of particle rotation on rings' dynamical evolution.
DE: 6035 Orbital and rotational dynamics
DE: 6040 Origin and evolution
DE: 6265 Planetary rings
SC: Planetary Sciences [P]
MN: Fall Meeting 2005