Three-Body Resonances in the Saturnian System

TL;DR

This study reveals that three-body resonances among Saturn's moons are common and significantly influence their orbital history, emphasizing the need to include these interactions in future dynamical models.

Contribution

The paper demonstrates through numerical simulations that three-body resonances played a crucial role in Saturn's satellite system, a factor previously overlooked in orbital history studies.

Findings

Three-body resonances are common in Saturn's satellite system.

These resonances are mainly of the eccentricity type and do not affect inclinations.

Some three-body resonances are near two-body resonances, others are isolated.

Abstract

Saturn has a dynamically rich satellite system, which includes at least three orbital resonances between three pairs of moons: Mimas-Tethys 4:2, Enceladus-Dione 2:1, and Titan-Hyperion 4:3 mean-motion resonances. Studies of the orbital history of Saturn's moons usually assume that their past dynamics was also dominated solely by two-body resonances. Using direct numerical integrations, we find that three-body resonances among Saturnian satellites were quite common in the past, and could result in a relatively long-term, but finite capture time (10 Myr or longer). We find that these three-body resonances are invariably of the eccentricity type, and do not appear to affect the moons' inclinations. While some three-body resonances are located close to two-body resonances (but involve the orbital precession of the third body), others are isolated, with no two-body arguments being near resonance. We conclude that future studies of the system's past must take full account of three-body resonances, which have been overlooked in the past work.