Neptune's ring arcs confined by coorbital satellites: dust orbital evolution through solar radiation

TL;DR

This study uses numerical simulations to explore how co-orbital satellites and Galatea confine Neptune's ring arcs, analyzing dust particle dynamics and their implications for arc stability and longevity.

Contribution

It introduces a model of four co-orbital satellites responsible for azimuthal confinement of Neptune's ring arcs, supported by detailed dust particle lifetime analysis.

Findings

Small particles in arcs last up to 50 years.

Approximately 20% of larger particles remain after 100 years.

Simulations predict particles should be present for at least 30 years.

Abstract

Voyager 2 images confirmed the presence of ring arcs around Neptune. These structures need a confinement mechanism to constrain their spreading due to collisions, dissipative forces, and differential keplerian motion. Here we report the results of a set of numerical simulations of the system formed by Neptune, the satellite Galatea, dust ring particles, and hypothetical co-orbital satellites. This dynamical system depicts a recent confinement mechanism formed by four co-orbital satellites being responsible for the azimuthal confinement of the arcs, while Galatea responds for their radial confinement. After the numerical simulations, the particles were divided into four groups: particles that stay in the arcs, transient particles, particles that leave the arcs to the Adams ring, and particles that collide with the co-orbital satellites. Our results showed that in all arcs the lifetime of the smaller particles is at most 50 years. After 100 years about 20% of the total amount of larger particles is still present in the arcs. From our numerical simulations, the particles should be present in all arcs after 30 years, the period between the discovery of the arcs up to now. Our results can not explain the disappearance of the leading arcs, Liberte and Courage unless the arcs are formed by different particle sizes. Analysis of the dust production, due to collisions between interplanetary debris onto the surface of the co-orbital satellites, ruled out the hypothesis that small satellites close to or in the arc the structure could be its source.