Mapping spiral waves and other radial features in Saturn's rings

TL;DR

This study analyzes high-quality Cassini images to identify and characterize spiral waves and radial features in Saturn's rings, providing new insights into their structure and resonant phenomena.

Contribution

It introduces a systematic wavelet-based method to detect radial structures, reports new classes of waves, and refines the surface density profile of Saturn's rings.

Findings

Identification of several new classes of waves

Refined radial surface density profile of Saturn's rings

An organized atlas of resonant features

Abstract

We have analyzed the highest-quality images to be obtained by Cassini of Saturn's main rings after the Saturn Orbit Insertion (SOI) and before the Ring Grazing Orbits (RGO) and Grand Finale (GF). These images are comparable to those of SOI in fidelity, though not in nominal resolution, due to their high signal-to-noise. We have systematically searched for radial structure in these images by reducing them to a single dimension (distance from Saturn's center) and using the continuous wavelet transform technique. We discuss the resonant theory of spiral waves and discuss the proper method for deriving the local surface density from the wavelet signature of a spiral wave. We present 1) individual features of interest found in our data, including several classes of waves that have not previously been reported; 2) a radial profile of surface density in Saturn's rings, which is more definitive for the A ring than any previously presented and which corrects some errors in previous profiles; and 3) an atlas of resonant features that indicates whether each feature is or is not expressed in the rings and that is organized graphically by resonance strength.