Physical collisions of moonlets and clumps with the Saturn's F-ring core

TL;DR

This study proposes that dissipative physical collisions between moonlets and the F-ring core are a plausible mechanism for creating the observed spirals and jets, supported by recent observational data and collision modeling.

Contribution

It introduces a new collisional mechanism involving moonlets and loose clumps to explain F-ring structures, supported by modeling and recent observations.

Findings

Collisions with low restitution coefficients (~0.1) reproduce the extent of spirals and jets.

Dissipative collisions are a viable mechanism for F-ring structure formation.

Recent data supports the presence of massive moonlets and collisional activity.

Abstract

Since 2004, observations of Saturn's F ring have revealed that the ring's core is surrounded by structures with radial scales of hundreds of kilometers, called "spirals" and "jets". Gravitational scattering by nearby moons was suggested as a potential production mechanism; however, it remained doubtful because a population of Prometheus-mass moons is needed and, obviously, such a population does not exist in the F ring region. We investigate here another mechanism: dissipative physical collisions of kilometer-size moonlets (or clumps) with the F-ring core. We show that it is a viable and efficient mechanism for producing spirals and jets, provided that massive moonlets are embedded in the F-ring core and that they are impacted by loose clumps orbiting in the F ring region, which could be consistent with recent data from ISS, VIMS and UVIS. We show also that coefficients of restitution as low as ~0.1 are needed to reproduce the radial extent of spirals and jets, suggesting that collisions are very dissipative in the F ring region. In conclusion, spirals and jets would be the direct manifestation the ongoing collisional activity of the F ring region.