A Traveling Feature in Saturn's Rings

TL;DR

This paper investigates how the orbital swaps of Saturn's co-orbital satellites Janus and Epimetheus affect the ring dynamics, revealing the launch of solitary waves traveling through Saturn's rings due to resonance shifts.

Contribution

It introduces the concept of a traveling feature in Saturn's rings caused by satellite orbital swaps and analyzes the resulting solitary wave phenomena.

Findings

Solitary waves are launched during satellite swaps.

Wave velocity is approximately twice the local density wave group velocity.

Resonance shifts significantly influence ring wave dynamics.

Abstract

The co-orbital satellites of Saturn, Janus and Epimetheus, swap radial positions every 4.0 years. Since \textit{Cassini} has been in orbit about Saturn, this has occurred on 21 January in 2006, 2010, and 2014. We describe the effects of this radial migration in the Lindblad resonance locations of Janus within the rings. When the swap occurs such that Janus moves towards Saturn and Epimetheus away, nonlinear interference between now-relocated density waves launches a solitary wave that travels through the rings with a velocity approximately twice that of the local spiral density wave group velocity in the A ring and commensurate with the spiral density wave group velocity in the B ring.