The effect of orbital damping during planet migration on the Inclination and Eccentricity Distributions of Neptune Trojans

TL;DR

This study investigates how planetary migration and damping of Neptune and Uranus's eccentricities and inclinations influence the formation and stability of high-inclination Neptune Trojans, proposing a resonant trapping mechanism as a key process.

Contribution

It introduces a new model showing that damping during planetary migration enhances the capture of high-inclination Neptune Trojans through secular resonances.

Findings

Most primordial NTs are unstable if damping occurs.

Damping increases the likelihood of NTs being captured into resonance.

Resonant trapping is a promising mechanism for NT formation.

Abstract

We explore planetary migration scenarios for formation of high inclination Neptune Trojans (NTs) and how they are affected by the planetary migration of Neptune and Uranus. If Neptune and Uranus's eccentricity and inclination were damped during planetary migration, then their eccentricities and inclinations were higher prior and during migration than their current values. Using test particle integrations we study the stability of primordial NTs, objects that were initially Trojans with Neptune prior to migration. We also study Trans-Neptunian objects captured into resonance with Neptune and becoming NTs during planet migration. We find that most primordial NTs were unstable and lost if eccentricity and inclination damping took place during planetary migration. With damping, secular resonances with Neptune can increase a low eccentricity and inclination population of Trans-Neptunian objects increasing the probability that they are captured into 1:1 resonance with Neptune, becoming high inclination NTs. We suggest that the resonant trapping scenario is a promising and more effective mechanism explaining the origin of NTs that is particularly effective if Uranus and Neptune experienced eccentricity and inclination damping during planetary migration.