Eurybates - the only asteroid family among Trojans?

TL;DR

This study confirms the existence of a unique collisional family among Jupiter's Trojan asteroids centered on Eurybates, and reports a potential new family around Ennomos, providing insights into asteroid family formation and surface processes.

Contribution

It identifies the only confirmed Trojan asteroid family around Eurybates and suggests a possible new family around Ennomos, advancing understanding of Trojan asteroid collisional history.

Findings

Eurybates family is dynamically and physically distinct from background asteroids.

A potential new family around Ennomos is identified, mainly composed of small asteroids.

Eurybates family has a well-defined collisional and dynamical model.

Abstract

We study orbital and physical properties of Trojan asteroids of Jupiter. We try to discern all families previously discussed in literature, but we conclude there is only one significant family among Trojans, namely the cluster around asteroid (3548) Eurybates. It is the only cluster, which has all of the following characteristics: (i) it is clearly concentrated in the proper-element space; (ii) size-frequency distribution is different from background asteroids; (iii) we have a reasonable collisional/dynamical model of the family. Henceforth, we can consider it as a real collisional family. We also report a discovery of a possible family around the asteroid (4709) Ennomos, composed mostly of small asteroids. The asteroid (4709) Ennomos is known to have a very high albedo $p_V \simeq 0.15$, which may be related to a hypothetical cratering event which exposed ice (Fern\'andez et al. 2003). The relation between the collisional family and the exposed surface of the parent body is a unique opportunity to study the physics of cratering events. However, more data are needed to confirm the existence of this family and its relationship with Ennomos.