On the tidal environment of an outwardly migrated F-ring

TL;DR

This study explores how the outward migration of Saturn's F-ring affects its structure and stability, revealing increased particle density and gravitational instability at certain radial positions due to altered tidal forces.

Contribution

It provides new insights into the effects of F-ring migration on particle density, velocity dispersions, and gravitational stability near the Roche limit.

Findings

Increased maximum particle density at ring edges with decreased tidal forces.

Radial velocity dispersions fall below escape velocity in dense regions.

Locations with Toomre Q<2 show higher particle instability.

Abstract

Saturns 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 parameters Q<2. Additionally, in locations of the ring where Q<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.