2026/07/29 by M. Ryleigh Davis, Matthew Belyakov, Ian Wong +2
Physics and Astronomy · #Astro and Planetary Science #Planetary Science and Exploration #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1126/sciadv.aeb1437
published as Davis, M.R., Belyakov, M., Wong, I., Milby, Z., and Brown, M.E. (2026). "Neptune's Inner Moons and Rings Are Exposed Icy Body Interiors." Science Advances, 12(31), eaeb1437 · This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science Advances on July 29, 2026
arxiv created 2026/07/29 · openalex publication_date 2026/07/29 · openalex created_date 2026/07/30 · arxiv updated 2026/07/31 · openalex updated_date 2026/07/31
Neptune's single large moon, Triton, is accompanied by a set of dusty rings and small moons whose composition and origin are uncertain. Using the James Webb Space Telescope, we observed Neptune's rings and three moons: Larissa, Galatea, and Proteus. These moons and rings have spectra that are distinct from other outer Solar System objects and show no evidence of water ice despite hosting deep 3-micrometer OH absorption bands. In addition, Larissa, Galatea, and the rings show a compositional signature unique among outer Solar System bodies: a 2.72-micrometer absorption band diagnostic of magnesium-rich phyllosilicates-a signpost of extensive aqueous alteration. These minerals likely formed in the interior of primordial satellites destroyed during Triton's violent capture or a tidally shredded dwarf planet. Our findings suggest that Neptune's present-day inner moons and rings reaccreted from this deep interior material and therefore uniquely access the interior composition of icy outer Solar System differentiated bodies.