Formation of satellites around large asteroids

The population of known satellites around asteroids larger than ~50 km are preferentially found orbiting primary bodies with rotation periods 5-6 h, which is significantly more rapid than an average body in this size range (10 hours). Similarly, primaries are more elongated than average as indicated by lightcurve amplitudes and direct imaging. Previous numerical modeling has found that satellite formation is possible in large collisions between asteroids, but these models did not track the shape and spin of remnant bodies. Therefore the relationship between successful satellite formation and remnant spin and shape haven’t been previously leveraged for understanding the key mechanisms at work.

Are the shape and spin of the primary indicative of specific impact scenario that preferentially produces satellites (e.g. oblique impacts)? Or, is rapid pre-impact rotation essential for satellite formation? We present here a series of impact models handed off to N-body gravitational models designed to answer these questions. The N-body models are done with a code capable of modeling granular mechanical interactions such that the evolving shape of the various remnants can be tracked throughout the reaccumulation process. We simulate head-on and oblique impacts into spherical targets that have a range of pre-impact rotation rates. We correlate produced shapes and spins of the largest remnants with metrics for satellite production intended to indicate likely production of long-lived satellites.