Secular evolution of a satellite by tidal effect. Application to Triton

TL;DR

This paper models the long-term tidal evolution of captured satellites, including spin dynamics, to explain their current orbital and geophysical properties, with a focus on Triton.

Contribution

It provides a comprehensive secular tidal evolution model that incorporates satellite spin evolution, applied specifically to Triton, to explain its current state.

Findings

Successfully explains Triton's geophysical properties.

Reproduces observed dynamical features of the Neptunian system.

Highlights importance of spin evolution in tidal modeling.

Abstract

Some of the satellites in the Solar System, including the Moon, appear to have been captured from heliocentric orbits at some point in their past, and then have evolved to the present configurations. The exact process of how this trapping occurred is unknown, but the dissociation of a planetesimal binary in the gravitational field of the planet, gas drag, or a massive collision seem to be the best candidates. However, all these mechanisms leave the satellites in elliptical orbits that need to be damped to the present almost circular ones. Here we give a complete description of the secular tidal evolution of a satellite just after entering a bounding state with the planet. In particular, we take into account the spin evolution of the satellite, which has often been assumed synchronous in previous studies. We apply our model to Triton and successfully explain some geophysical properties of this satellite, as well as the main dynamical features observed for the Neptunian system.