An improved semi-empirical model of catastrophic impact processes .1. Theory and laboratory experiments

Several improvements to the semi-empirical approach to the physics of catastrophic breakup events (see P. Paolicchi, A. Cellino, P. Farinella, and V. Zappala, Icarus 77, 187-212, 1989) have been recently developed and are described in the present paper, The main new features of the model consist of the derivation of a set of realistic, non-overlapping fragments, as well as of a better treatment of the role played by gravitational effects. The main physical results obtained by means of the improved model in situations similar to those encountered in laboratory experiments are discussed, and compared with the experimental evidence and with the outcomes of hydrodynamical simulations, as well as with the analogous results found in the previous version of the model, The present model appears as being able to fit, also quantitively, the experiments, and to enlight hidden interrelations among various observed properties, in spite of its simplified physics, The problems related to the possibility of deriving reliable fragment mass distributions are pointed out and extensively discussed, The systematic extension of the present model to the cases in which gravitational effects are dominating will be postponed to a forthcoming paper. (C) 1996 Academic Press, Inc.