Physical characteristics and non-keplerian orbital motion of "propeller" moons embedded in Saturn's rings

TL;DR

This paper reports the discovery of large, trackable 'propeller' moons in Saturn's rings, revealing their non-Keplerian orbital behavior and providing insights into their sizes and properties.

Contribution

It presents the first observation of individual embedded moons in Saturn's rings and demonstrates their sustained non-Keplerian orbital motion.

Findings

Discovered large propeller moons in Saturn's rings.

Tracked moonlets over 5 years using Cassini data.

Observed non-Keplerian orbital motion of propellers.

Abstract

We report the discovery of several large "propeller" moons in the outer part of Saturn's A ring, objects large enough to be followed over the 5-year duration of the Cassini mission. These are the first objects ever discovered that can be tracked as individual moons, but do not orbit in empty space. We infer sizes up to 1--2 km for the unseen moonlets at the center of the propeller-shaped structures, though many structural and photometric properties of propeller structures remain unclear. Finally, we demonstrate that some propellers undergo sustained non-keplerian orbit motion. (Note: This arXiv version of the paper contains supplementary tables that were left out of the ApJL version due to lack of space).