[astro-ph.EP] 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. Remarkably, 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 micron OH absorption bands.
Additionally, Larissa, Galatea, and the rings show a compositional signature unique among outer solar system bodies: a 2.72 micron 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.
M. Ryleigh Davis, Matthew Belyakov, Ian Wong, Zachariah Milby, Michael E. Brown
Comments: 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
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2607.27481 [astro-ph.EP] (or arXiv:2607.27481v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2607.27481
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Journal reference: 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
Related DOI:
https://doi.org/10.1126/sciadv.aeb1437
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Submission history
From: M. Ryleigh Davis
[v1] Wed, 29 Jul 2026 21:48:22 UTC (467 KB)
https://arxiv.org/abs/2607.27481
Astrobiology, Astrogeology, Astrochemistry,
