Discovery of a young subfamily of the (221) Eos asteroid family

Abstract

In this work we report the discovery of a young cluster of asteroids that originated by the breakup of an asteroid member of the (221)Eos family. By applying the Hierarchical clustering method to the catalog of proper elements we have identified 26 members of this new small group of asteroids. We have established that the statistical significance of this cluster is $>99\%$, therefore it corresponds to a real asteroid family, named the (633)Zelima cluster, after its lowest numbered member. The orbits of its members are dynamically stable, a fact that enabled us to use the backward integration method, in two variants to identify potential interlopers and estimate its age. Applying it first on the orbits of the nominal family members we identified three asteroids as interlopers. Then we applied it on a set of statistically equivalent clones of each member to determine the age of the cluster, with a result of $2.9\pm0.2$Myrs.