Variation of particle size distribution in Saturn's rings and search for density waves in Uranus rings.

摘要

bimodal size distribution for particles in Saturn's rings has been determined via an analysis of PPS, UVS and RSS occultation data. The variation of the size distribution in featureless regions indicates that the dust variation is nearly constant in the Saturn's rings and exhibits a slight anti-correlation with 1 cm sized particles. Sub-centimeter sized particles increase outward in the rings, with a maximum in the B ring, similar to the variation of 1 cm sized particles. However, the ratio of subcentimeter sized particles to 1 cm sized particles does not vary significantly in the rings. Janus 5:4 density wave differs significantly from the featureless regions. The amount of dust is greater by a factor of about 2. Both dust and sub-centimeter sized particles are strongly anti-correlated with 1 cm sized particles. Partial formation of gaps is evident for both sub- and supra-centimeter sized particles, consistent with the predictions of Goldreich and Tremaine (1978). Dust is insensitive to the gravitational torque associated with the resonance. Our results are also consistent with Dones (1987). In wave regions, large particles collide and produce dust and do not break up into smaller particles. We searched the Uranian rings, via time series analysis methods, to identify periodic phenomena in the rings. A possible wave-like feature has been identified in both the