Are Two of the Neptune Trojans Dynamically Unstable?

TL;DR

This study investigates the dynamical stability of two Neptune Trojans, suggesting they may be unstable and captured objects, which has implications for understanding their origin and the population's evolution.

Contribution

The paper provides dynamical analyses of two Neptune Trojans, revealing their proximity to stability boundaries and supporting the hypothesis of their captured origin.

Findings

Both objects are near stability-unstability boundaries.

There is a significant probability of their instability within hundreds of millions of years.

Their instability supports the captured origin hypothesis.

Abstract

The Neptune Trojans are the most recently discovered population of small bodies in the Solar System. To date, only eight have been discovered, though it is thought likely that the total population at least rivals that of the asteroid belt. Their origin is still the subject of some debate. Here, we detail the results of dynamical studies of two Neptune Trojans, 2001 QR322 and 2008 LC18. We find that both objects lie very close to boundaries between dynamically stable and unstable regions, with a significant probability that either or both of the objects are actually unstable on timescales of a few hundred million years. Such instability supports the idea that at least these two Neptune Trojans are dynamically captured objects, rather than objects that formed in situ. This that does not, however, rule out the possibility that these two objects were captured during Neptune's proposed post-formation migration, and have remained as Trojans ever since.