Prometheus Induced Vorticity In Saturns F Ring

TL;DR

This study investigates how Prometheus's gravitational influence induces vorticity and local turbulence in Saturn's F ring, revealing transient vortex formations and high dispersions that could impact ring dynamics and planet formation.

Contribution

It provides the first numerical evidence of Prometheus-induced vorticity and turbulence in Saturn's F ring, highlighting the transient nature of vortices and their potential role in planetary disk processes.

Findings

Elevated vorticity persists for 1-3 orbital periods post encounter.

Channel edges exhibit high radial dispersions (~20-50 cm/s).

Potential sites for coherent object growth are identified away from immediate edges.

Abstract

Saturns rings are known to show remarkable real time variability in their structure. Many of which can be associated to interactions with nearby moons and moonlets. Possibly the most interesting and dynamic place in the rings, probably in the whole Solar System, is the F ring. A highly disrupted ring with large asymmetries both radially and azimuthally. Numerically non zero components to the curl of the velocity vector field (vorticity) in the perturbed area of the F ring post encounter are witnessed, significantly above the background vorticity. Within the perturbed area rich distributions of local rotations is seen located in and around the channel edges. The gravitational scattering of ring particles during the encounter causes a significant elevated curl of the vector field above the background F ring vorticity for the first 1-3 orbital periods post encounter. After 3 orbital periods vorticity reverts quite quickly to near background levels. This new found dynamical vortex life of the ring will be of great interest to planet and planetesimals in proto-planetary disks where vortices and turbulence are suspected of having a significant role in their formation and migrations. Additionally, it is found that the immediate channel edges created by the close passage of Prometheus actually show high radial dispersions in the order ~20-50 cm/s, up to a maximum of 1 m/s. This is much greater than the value required by Toomre for a disk to be unstable to the growth of axisymmetric oscillations. However, an area a few hundred km away from the edge shows a more promising location for the growth of coherent objects.