On the tidal environment of an outwardly migrating F ring

Abstract

Saturn's F ring is a unique narrow ring that lies (radially) close to the tidally disruptive Roche limit of water ice for Saturn. Significant work has been done that shows it to be one of the most dynamic places in the Solar system. Aggregates that are fortunate enough to form constantly battle against the strong tidal forces of Saturn and the nearby moons Prometheus and Pandora, which act to gravitationally stir up ring material. Planetary rings are also known to radially spread. Therefore, as the F ring lies at the edge of the main rings, we investigate the effect of an outwardly migrated F ring and its interaction with Prometheus. An increase in the maximum number density of particles at the channel edges is observed with decreasing local tidal environment. Radial velocity dispersions are also observed to fall below the typical escape velocity of a 150m icy moonlet (< 10 cm s-1) where density is enhanced, and are gravitationally unstable with Toomre parametersQ < 2. Additionally, in locations of the ring whereQ < 2 is observed, more particles are seen to fall below or close to the critical Toomre parameter as the radial location of the ring increases.