JWST Reveals the Kuiper Belt–like Compositions of the Uranian Rings and Small Moons
- 1California Institute of Technology
- 2Space Telescope Science Institute
Abstract
We present the JWST NIRSpec 1–5 μ m spectra of the Uranian rings and four ring moons: Puck, Perdita, Portia, and Juliet. We find that the compositions of the rings and moons strongly resemble water-type Kuiper Belt objects, showing deep 3.0 μ m O–H and water-ice features as well as the CO ₂ band at 4.27 μ m. The volatiles show a radial trend of decreasing volatile abundance at closer radial distance to the planet, consistent with recent estimates of the densities of the innermost moons. Given the observed compositional signatures, we suggest two ways to reconcile the history of the small inner moons with that of the regular ones. The first is that the Uranus-tilting collision produced a disk from an impactor formed out of material similar to that which comprises water-rich Kuiper Belt objects, and the ring moons are small undifferentiated remnants of that process. Alternatively, the rings and ring moons postdate the formation of the regular moons, and formed from the later tidal disruption of a several-hundred-kilometer-sized, undifferentiated, water-type Kuiper Belt object.
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BibTeX
@article{belyakov2026jwst,
title = {{JWST Reveals the Kuiper Belt–like Compositions of the Uranian Rings and Small Moons}},
author = {Matthew Belyakov and M. Ryleigh Davis and Zachariah Milby and Ian Wong and Michael E. Brown},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = oct,
doi = {10.3847/2041-8213/aeacc0},
url = {https://iopscience.iop.org/article/10.3847/2041-8213/aeacc0},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - JWST Reveals the Kuiper Belt–like Compositions of the Uranian Rings and Small Moons
AU - Matthew Belyakov
AU - M. Ryleigh Davis
AU - Zachariah Milby
AU - Ian Wong
AU - Michael E. Brown
PY - 2026
DA - 2026/10/09
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/aeacc0
UR - https://iopscience.iop.org/article/10.3847/2041-8213/aeacc0
AB - We present the JWST NIRSpec 1–5 μ m spectra of the Uranian rings and four ring moons: Puck, Perdita, Portia, and Juliet. We find that the compositions of the rings and moons strongly resemble water-type Kuiper Belt objects, showing deep 3.0 μ m O–H and water-ice features as well as the CO ₂ band at 4.27 μ m. The volatiles show a radial trend of decreasing volatile abundance at closer radial distance to the planet, consistent with recent estimates of the densities of the innermost moons. Given the observed compositional signatures, we suggest two ways to reconcile the history of the small inner moons with that of the regular ones. The first is that the Uranus-tilting collision produced a disk from an impactor formed out of material similar to that which comprises water-rich Kuiper Belt objects, and the ring moons are small undifferentiated remnants of that process. Alternatively, the rings and ring moons postdate the formation of the regular moons, and formed from the later tidal disruption of a several-hundred-kilometer-sized, undifferentiated, water-type Kuiper Belt object.
SN - 2041-8205
SN - 2041-8213
ER -