Year: 2024
Type: article
Abstract: Here we review the origin, evolution, and compositional properties of Saturn’s ring moons. This class of eleven small satellites includes objects orbiting near the outer edge of the main rings (Pan, Daphnis, Atlas, Prometheus, Pandora, Janus, Epimetheus) and “ring-embedded” moons (Aegeon, Methone, Anthe, Pallene) orbiting inward of Enceladus and associated with either diffuse or partial rings. We discuss current formation scenarios, according to which ring moons could originate either in the main rings from accretion onto original seeds denser than the ring material, or outside the A ring from spontaneous accretion of ring particles, and then evolve outwards due to gravitational torque from the rings. Remote sensing observations of the ring moons from the Cassini mission are analyzed in the broader context of Saturn’s icy moons and main rings observations. Spectroscopic data support a compositional paradigm similar to the main rings, dominated by water ice, and smaller amounts of two separate contaminants, in the form of a UV absorber and a spectrally neutral darkening material. Global radial trends in the spectral properties of the ring moons suggest that the surface composition is significantly affected by a complex interplay of exogenous processes, among which the contamination from nearby A ring particles, meteoritic bombardment, charged particle flux, and E ring particle accumulation, depending on the corresponding magnitude at the ring moon orbital distance and exposure time. These processes modify the original composition inherited by the rings and, coupled with the fact that the surface composition is likely representative only of the ring moon outer layers, make it difficult to trace back the present composition to a given ring moon formation scenario.
Source: Space Science Reviews
Institutions: Institute for Space Astrophysics and Planetology, National Institute for Astrophysics, Cornell University, University of Idaho, Centre National de la Recherche Scientifique, Institut de physique du globe de Paris, Université Paris Cité, Ames Research Center, Southwest Research Institute, Planetary Science Institute, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, Institut de Mécanique Céleste et de Calcul des Éphémérides, Institut Universitaire de France, Aix-Marseille Université
Language: English
Topic: Astro and Planetary Science
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,890
OpenAlex ID: W4402600930