Effects of Exogenic Dust on Uranus' Rings and Seasonal Variations

The rings of Uranus, composed primarily of dark, radiation-processed material, are constantly subjected to exogenic dust bombardment, which affects their composition, structure, long-term dynamics, and evolution. This research investigates the interaction of Uranus’ rings with exogenic dust, focusing on the unique seasonal dynamics driven by Uranus' extreme axial tilt of 97.8 degrees. Uranus’ tilted rotational axis likely causes seasonal variations in dust flux, resulting in asymmetrical deposition patterns and impact rates depending on its orbital position around the Sun. Micrometeoroid particles near Saturn and Jupiter provide valuable analogs for studying Uranus, as they can be categorized into interplanetary dust particles (IDPs) and interstellar dust (ISD), depending on whether their orbits are sun-bound or sun-unbound, respectively. ISD originates primarily from the local interstellar cloud (LIC) and enters the solar system in a highly directional stream, while IDPs come from sources such as comets, Oort-Cloud and Edgeworth-Kuiper Belt objects (EKBs). These dust grains, subject to forces like Poynting–Robertson drag, lose momentum and spiral inward toward the inner solar system. Colwell et al. (1998) demonstrated that interstellar and interplanetary dust particles entering the Jovian magnetosphere can be captured through energy and angular momentum exchange, eventually forming a tenuous dust ring. A similar mechanism might occur in Uranus' rings, where dust interactions play an essential role in the rings' long-term evolution. These variations are hypothesized to cause observable differences in ring over Uranus' 84-year orbital period. In this study, we explore how impacting dust transfers angular momentum and energy to Uranus' rings, leading to gradual spreading and potential long-term erosion. Also, we model impact patterns from high-velocity dust collisions, which could maintain Uranus' faint rings and influence their overall dynamics. Future missions with advanced instrumentation may provide crucial data to validate these predictions and further explore Uranus’ ring system.