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arXiv · 2608.16078

Stability Mapping of the New Uranian Moon S/2025 U1 with Updated Masses for Cordelia, Ophelia, and Cressida

J. Xavier·A. Amarante·S. Giuliatti Winter·A. Ferreira
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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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J. Xavier, A. Amarante, S. Giuliatti Winter, A. Ferreira. 2026-09-02. Stability Mapping of the New Uranian Moon S/2025 U1 with Updated Masses for Cordelia, Ophelia, and Cressida. https://doi.org/10.1051/0004-6361%2F202558328

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