Formation of Asteroid Families and Delivery of NEO Showers from the Main Belt

Abstract

Dynamical families are the observable outcomes of collisional events that occurred in the asteroid Main Belt. They are critically important in many respects. First, they are major sources of information about the physics governing the processes of catastrophic break-up. Second, families give some unique opportunities to understand the structures and internal compositions of asteroidal bodies. Third, they provide essential constraints on the plausible collisional history of the Main Belt. Last but not least, family-forming events have been proven to play an important role as sources of near-Earth objects (NEOs). In particular, injection of very large numbers of objects into the region of the terrestrial planets, over relatively short timescales, eventually occurred when some of the major families presently known were formed. These asteroid showers are expected to have affected the cratering history of the inner planets, and to have temporarily increased the NEO population very much above the supposedly steady-state inventory.