Catastrophic planetesimal collision

A catastrophic planetesimal collision has $Q\ge Q_D^{\ast }$ and disperses a substantial fraction of the target mass.

The catastrophic planetesimal collision rate is the collision rate integrated over impactors large enough to satisfy $Q\ge Q_D^{\ast }$.

The catastrophic collision mass-loss timescale is the target mass divided by the rate at which catastrophic impacts remove mass from its largest remnant.