# Seasonal structures in Saturn's dusty Roche Division correspond to periodicities of the planet's magnetosphere

## TL;DR

This study links periodic dusty structures in Saturn's Roche Division to variations in Saturn's magnetospheric periods, revealing dynamic interactions between the planet's magnetic environment and ring structures over time.

## Contribution

It demonstrates a correlation between magnetospheric periodicities and dust structures in Saturn's Roche Division, introducing a model of magnetic perturbations affecting ring features.

## Key findings

- Dusty structures vary with magnetospheric periods.
- Resonances shift between the Roche Division and A ring.
- Magnetic field oscillations are of a few nanotesla.

## Abstract

We identify multiple periodic dusty structures in Saturn's Roche Division, a faint region spanning the $\sim3000$ km between the A and F rings. The locations and extent of these features vary over Cassini's tour of the Saturn system, being visible in 2006 and 2016-2017, but not in 2012-2014. These changes can be correlated with variations in Saturn's magnetospheric periods. In 2006 and 2016-2017, one of the drifting magnetospheric periods would produce a 3:4 resonance within the Roche Division, but in 2012-2014 these resonances would move into the A ring as the magnetospheric periods converged. A simple model of magnetic perturbations indicates that the magnetic field oscillations responsible for these structures have amplitudes of a few nanotesla, comparable to the magnetic field oscillation amplitudes of planetary period oscillations measured by the magnetometer onboard Cassini. However, some previously unnoticed features at higher radii have expected pattern speeds that are much slower than the magnetospheric periodicities. These structures may reflect an unexpectedly long-range propagation of resonant perturbations within dusty rings.