07/Jun/19 – The population of fission clusters inside collisional asteroid families (Valerio Carruba, UNESP)

Asteroid families are groups of objects sharing similar orbits. They are mostly the results of past collisions between two asteroids.   Recent studies have shown that some asteroid families can also be the outcome of the spin-up induced fission of a secondary body (fission clusters). In at least four young fission clusters, more than 5% of their members belong to sub-families, that mostly formed after the main fission event.  Using family recognition methods based on time-reversal dynamical simulations, machine-learning clustering algorithms, and the exceptional orbit accuracy obtained from Gaia observations of Solar System Objects, we identify several sub-clusters within extremely young collisional families. Collisional asteroid families younger than 100 Myr have a higher fraction of detectable fission sub-clusters with respect to older groups.  The collisional events  that form asteroid families may, therefore, trigger a subsequent cascade of spin-induced formations of fission clusters.