The gravitational instability of a stream of co-orbital particles

TL;DR

This paper investigates the gravitational instability of co-orbital particle streams, using mathematical modeling and simulations to understand their evolution, stability, and potential for aggregate formation, with implications for planetary rings.

Contribution

It introduces a detailed analysis of gravitational instability in co-orbital particle streams using the shearing sheet model and N-body simulations, revealing new insights into their nonlinear evolution and aggregate formation.

Findings

Identification of linear instability features

Observation of system spreading and disordered states

Discovery of a connection to magnetorotational instability

Abstract

We describe the dynamics of a stream of equally spaced macroscopic particles in orbit around a central body (e.g. a planet or star). A co-orbital configuration of small bodies may be subject to gravitational instability, which takes the system to a spreading, disordered and collisional state. We detail the linear instability's mathematical and physical features using the shearing sheet model and subsequently track its nonlinear evolution with local N-body simulations. This model provides a convenient tool with which to understand the gravitational and collisional dynamics of narrow belts, such as Saturn's F-ring and the streams of material wrenched from tidally disrupted bodies. In particular, we study the tendency of these systems to form long-lived particle aggregates. Finally, we uncover an unexpected connection between the linear dynamics of the gravitational instability and the magnetorotational instability.