Thermal Evolution of Uranus with a Frozen Interior

TL;DR

This paper proposes that Uranus's faintness is due to a predominantly frozen interior with high viscosity, which traps heat and aligns with observed orbital dynamics.

Contribution

It introduces a thermal evolution model incorporating a frozen, high-viscosity interior to explain Uranus's low luminosity and satellite orbital evolution.

Findings

Uranus's interior is likely over 50% solid.

High-viscosity interior models match Uranus's faintness.

Frozen interior explains satellite orbital evolution.

Abstract

The intrinsic luminosity of Uranus is a factor of 10 less than that of Neptune, an observation that standard giant planetary evolution models, which assume negligible viscosity, fail to capture. Here we show that more than half of the interior of Uranus is likely to be in a solid state, and that thermal evolution models that account for this high viscosity region satisfy the observed faintness of Uranus by storing accretional heat deep in the interior. A frozen interior also explains the quality factor of Uranus required by the evolution of the orbits of its satellites.