The velocity-size relationship for members of asteroid families and implications for the physics of catastrophic collisions

An extensive analysis of the size-ejection velocity relationship for member s of several of the most important asteroid families identified in the Main Belt is presented. We have found a well defined behavior, with smaller fra gments having on the average higher ejection velocities. The results provid e useful constraints to current models of catastrophic breakup processes an d lead also to a new estimate of the transition limit in largest remnant/pa rent body mass ratio, distinguishing cratering, and shattering regimes. Mor eover, we have now available a practical method for estimating fragment eje ction velocities in interasteroid collisional events. This can be easily im plemented in numerical models of the collisional evolution of the asteroid belt. In particular, it should be possible to undertake a more quantitative assessment of the efficiency of collisional events in the Main Belt as the sources of near Earth asteroids of different sizes. (C) 1999 Academic Pres s.