The Trojan-like Colors of Low-Perihelion Kuiper Belt Objects

TL;DR

This study investigates the origins of Jupiter Trojans by identifying a Kuiper belt sub-population with Trojan-like colors, suggesting a shared source and providing insights into early Solar System evolution.

Contribution

It reveals a dynamical sub-population of low-perihelion Kuiper belt objects with Trojan-like colors, linking them to Jupiter Trojans and advancing understanding of their common origin.

Findings

Low-perihelion KBOs have colors similar to Jupiter Trojans.

Centaurs exhibit redder, Kuiper belt-like colors.

Scattered disk objects contribute significantly to low-perihelion KBOs.

Abstract

An important testable prediction of dynamical instability models for the early evolution of the Solar System is that Jupiter Trojans share a source population with the Kuiper belt. Concrete evidence of this prediction remains elusive, as Kuiper belt objects (KBOs) and Jupiter Trojans appear to have different surface compositions. We address the long-standing question of Trojan origin by finding a dynamical sub-population in the Kuiper belt with Trojan-like colors. Combining existing photometric data with our own surveys on Keck I and Palomar P200, we find that the low-perihelion ($q<30 $AU, $a>30 $AU) component of the Kuiper belt has colors that bifurcate similarly to the Jupiter Trojans, unlike Centaurs ($a<30 $AU) which have redder, Kuiper belt-like colors. To connect the Jupiter Trojans to the Kuiper belt, we test whether the distinct Trojan-like colors of low-perihelion KBOs result from surface processing, or are sourced from a specific population in the Kuiper belt. By simulating the evolution of the Canada-France Ecliptic Plane Survey synthetic population of KBOs for four billion years, we find that differences in heating timescales cannot result in a significant depletion of Very Red low-perihelion KBOs as compared to the Centaurs. We find that the neutrally-colored scattered disk objects ($e>0.6$ KBOs) contribute more to the low-perihelion KBO population rather than Centaurs, resulting in their different colors.