Trailing (L5) Neptune Trojans: 2004 KV18 and 2008 LC18

TL;DR

This study investigates the dynamical behaviors of two recently discovered Neptune Trojans, revealing one as a temporary object and the other as a potentially long-term stable member, with implications for understanding Solar system evolution.

Contribution

The paper provides the first detailed dynamical analysis of the trailing Neptune Trojans 2004 KV18 and 2008 LC18, highlighting their stability differences and the need for further observations.

Findings

2004 KV18 is a temporary Neptune Trojan, likely captured around 203,000 years ago.

2008 LC18 shows potential for long-term stability, with some clones surviving up to 4 billion years.

Stability depends strongly on orbital parameters, emphasizing the need for precise observations.

Abstract

The population of Neptune Trojans is believed to be bigger than that of Jupiter Trojans and that of asteroids in the main belt, although only eight members of this far distant asteroid swarm have been observed up to now. Six leading Neptune Trojans around the Lagrange point L4 discovered earlier have been studied in detail, but two trailing ones found recently around the L5 point, 2004 KV18 and 2008 LC18, have not been investigated yet. In this paper, we report our investigations on the dynamical behaviors of these two new Neptune Trojans. Our calculations show that the asteroid 2004 KV18 is a temporary Neptune Trojan. Most probably, it was captured into the trailing Trojan cloud no earlier than 203kyr ago, and it will not keep this identity no later than 165kyr in future. Based on the statistics on our orbital simulations, we argue that this object is more like a scattered Kuiper belt object. On the contrary, the orbit of asteroid 2008 LC18 is much more stable. Among the clone orbits spread within the orbital uncertainties, a considerable portion of clones may survive on the L5 tadpole orbits for 4Gyr. The strong dependence of the stability on the semimajor axis and resonant angle suggests that further observations are badly needed to confine the orbit in the stable region. We also discuss the implications of the existence and dynamics of these two trailing Trojans on the Solar system history.