The formation of binary asteroids as outcomes of catastrophic collisions

A semi-empirical model of catastrophic break-up processes among asteroids is used to investigate the possibility that binary asteroids could be formed by collisional events. In particular, numerical integrations of the dynamical evolution of fragments under the effect of mutual gravitational interactions after ejection are performed for a set of simulations, in order to detect the possible formation of binary systems. The results suggest that the occurrence of binaries formed by couples of fragments of comparable mass is fairly rare. Therefore it is estimated that such systems could exist but they should not be very frequent in the asteroid belt. On the other hand, binaries with very small mass ratios, like the Ida-Dactyl binary system, might be more frequent. However, in these cases fragments are dealt with in a size range which is poorly sampled by the model. For this reason, some more detailed analysis seems necessary for assessing more reliably the efficiency of break-up phenomena as sources of Ida-Dactyl-like systems.