Stability Mapping of the New Uranian Moon S/2025 U1 with Updated Masses for Cordelia, Ophelia, and Cressida
astro-ph.EP
Submitted: 2026-08-17
Updated: 2026-09-02
Comments: 18 pages, 15 figures, and 6 tables. Accepted for publication in Section 10 (Planets, planetary systems, and small bodies) of Astronomy & Astrophysics (A&A). Final proof
Journal ref: Astronomy & Astrophysics (A&A) 2026
DOI: 10.1051/0004-6361/202558328
License: http://creativecommons.org/licenses/by/4.0/
The gist: We investigate the dynamics of Uranus's inner satellite system considering three recent updates: the inclusion of the new moon S/2025 U1, revised mass estimates for Cordelia, Ophelia, and Cressida,
Terminology
Abstract
We investigate the dynamics of Uranus's inner satellite system considering three recent updates: the inclusion of the new moon S/2025 U1, revised mass estimates for Cordelia, Ophelia, and Cressida, and updated zonal harmonic coefficients (J 2, J 4, and J 6). Using numerical integrations, mean-motion resonance analysis, and Frequency Map Analysis (FMA), we explore their impact on orbital stability. For the first time, we analyze the dynamics of the newly discovered moon S/2025 U1 and find that it follows a stable orbit, exhibiting smooth variations in its orbital elements over 250,000 years. Depending on the adopted radius, the gravitational influence of S/2025 U1 on the surrounding region is more compatible with a body of approximately 5-7 km radius, producing diffusion maps associated with a regular orbital evolution. Furthermore, the case R = 7 km shows a reduction in the diffusion of neighboring satellites, suggesting a possible local stabilizing effect on the system's orbital evolution. We also identified inner and outer regions of low diffusion around its orbit, suggesting that the dynamical environment is compatible with survival of coorbital particles or additional small satellites. In contrast, very high radius values, particularly R = 20 km, tend to increase diffusion among neighboring satellites, making this scenario less compatible with a dynamically stable orbital configuration. We further explore the survival of hypothetical satellites near S/2025 U1. Our results show that bodies with masses up to 3 times that of S/2025 U1 can remain stable in both the interior (between S/2025 U1 and Ophelia) and the exterior (between S/2025 U1 and Bianca) of its orbit. Finally, Cressida, Desdemona, Juliet, and Portia are most sensitive to updated parameters. Most resonances circulate, while Belinda-Perdita 44:43 confines the system with reduced libration amplitude.
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