# Primordial migration of co-orbital satellites as a mechanism for the horseshoe orbit of Janus-Epimetheus

## TL;DR

This study investigates how primordial migration and disruption of a guiding satellite can naturally lead to the horseshoe co-orbital orbit configuration of Janus and Epimetheus around Saturn, using detailed numerical simulations.

## Contribution

It demonstrates that horseshoe co-orbital orbits can emerge naturally from the disruption of a guiding satellite in a circumplanetary disk, providing a new formation mechanism.

## Key findings

- Horseshoe orbits appear as a natural outcome after satellite disruption.
- Numerical simulations support the primordial migration hypothesis.
- The model explains the current co-orbital configuration of Janus and Epimetheus.

## Abstract

We analyze the orbital motion of two natural satellites initially in co-orbital configuration with a third (guiding) satellite embedded into a circumplanetary gas disc and undergoing tidal interactions with the central planet. By solving the exact equations of motion, including the dissipative effects and the mutual gravitational perturbations, we investigate the configuration of the system soon after the guiding satellite is disrupted when crossing the Roche limit with the central planet during its orbital decay. The application is done for the system composed of Saturn and the two small co-orbital satellites Janus and Epimetheus. We perform a large number of numerical simulations, varying the mass of the hypothetical guiding satellite, Saturn's tidal quality factor and the initial configuration and the masses of the small satellites. Analyzing the orbital configurations of Janus and Epimetheus soon after the disruption of the guiding satellite, we obtain that the mutual horseshoe co-orbital orbits appear as a natural outcome of the numerical simulations.