Saturn's moons Aegaeon, Anthe, and Methone and their surrounding ring arcs are in corotation resonances with Saturn's moon Mimas that cause their semi-major axes to oscillate stably every few years. These resonances also longitudinally confine debris launched from these moons into arcs. How these moons became trapped in these resonances is still not well understood. Also, it is unclear why Aegaeon is the closest to exact resonance. We simulate orbits of multiple massive bodies in a corotation resonance in order to better understand these systems. In these simulations, the bodies exchange angular momentum and energy during close encounters, altering their orbits. Nevertheless, since a typical encounter occurs on a timescale that is short compared to the synodic period of Mimas, the relationships between the energy transferred by the encounter and the locations of the objects relative to the sites of exact corotation is more complex than one might expect. It is at least clear that more massive bodies are more likely to remain in the corotation resonance, while less massive bodies are more likely to exit it. This can explain why Aegaeon has remained in the corotation resonance with Mimas, but does not explain why it is so close to exact resonance. Further investigation of these interactions may be relevant to understand denser systems like the arcs in Neptune's Adams ring and how they can be maintained despite frequent inelastic collisions.
AAS/Division for Planetary Sciences Meeting Abstracts #50
- Pub Date:
- October 2018