# Axisymmetric density waves in Saturn's rings

## TL;DR

This paper reports the discovery and analysis of axisymmetric density waves in Saturn's rings, which are excited by interactions between satellite resonances and normal mode oscillations, differing from typical spiral density waves.

## Contribution

It identifies a new type of density wave in Saturn's rings and explains its excitation mechanism involving interference between satellite resonances and normal modes.

## Key findings

- Discovery of axisymmetric density waves in Saturn's rings.
- Proposed excitation mechanism involving resonance interference.
- Potential presence of similar waves near other ring edges.

## Abstract

Density waves in Saturn's rings are usually tightly wrapped spiral patterns generated by resonances with either Saturn's moons or structures inside the planet. However, between the Barnard and Bessel Gaps in the Cassini Division (i.e. between 120,240 and 120,300 km from Saturn's spin axis), there are density variations that appear to form an axisymmetric density wave consisting of concentric zones of varying densities that propagate radially through the rings. Axisymmetric waves cannot be generated directly by a satellite resonance, but instead appear to be excited by interference between a nearby satellite resonance and normal mode oscillations on the inner edge of the Barnard Gap. Similar axisymmetric waves may exist just interior to other resonantly confined edges that exhibit a large number of normal modes, including the Dawes ringlet in the outer C ring and the outermost part of the B ring.