Composition of the L5 Mars Trojans: Neighbors, not Siblings

TL;DR

This study analyzes the compositions of the two largest L5 Mars Trojans using infrared spectroscopy, revealing they likely originate from different parent bodies and are not siblings, with analogs to meteorites.

Contribution

It provides new spectral data confirming diverse origins of Mars Trojans and identifies meteorite analogs for their compositions.

Findings

5261 Eureka resembles angrite meteorites.

101429 1998 VF31 has varied meteorite analogs.

Mars Trojans are compositionally diverse and not from a common parent.

Abstract

Mars is the only terrestrial planet known to have Tro jan (co-orbiting) asteroids, with a confirmed population of at least 4 objects. The origin of these objects is not known; while several have orbits that are stable on solar-system timescales, work by Rivkin et al. (2003) showed they have compositions that suggest separate origins from one another. We have obtained infrared (0.8-2.5 micron) spectroscopy of the two largest L5 Mars Tro jans, and confirm and extend the results of Rivkin et al. (2003). We suggest that the differentiated angrite meteorites are good spectral analogs for 5261 Eureka, the largest Mars Trojan. Meteorite analogs for 101429 1998 VF31 are more varied and include primitive achondrites and mesosiderites.