SPH simulations of high-speed collisions between asteroids and comets

We studied impact processes by means of smoothed-particle hydrodynamics (SPH) simulations. The method was applied to modelling formation of main-belt families during the cometary bombardment (either early or late, ∼3.85Gy ago). If asteroids were bombarded by comets, as predicted by the Nice model, hundreds of asteroid families (catastrophic disruptions of diameter D≥100km bodies) should have been created, but the observed number is only 20. Therefore we computed a standard set of 125 simulations of collisions between representative D=100km asteroids and high-speed icy projectiles (comets), in the range 8 to 15km/s. According to our results, the largest remnant mass M_lr is similar as in low-speed collisions, due to appropriate scaling with the effective strength Q_eff, but the largest fragment mass M_lf exhibits systematic differences — it is typically smaller for craterings and bigger for super-catastrophic events. This trend does not, however, explain the non-existence of old families. The respective parametric relations can be used in other statistical (Monte-Carlo) models to better understand collisions between asteroidal and cometary populations.