CONICET | Buscador de Institutos y Recursos Humanos

It is usually believed that planetary formation is a two-step process. During the first step, the ``so called'' planetesimals are formed while during the second step the terrestrial planets and the cores of the gaseous planets are formed from the accretion of planetesimals. At present, the size of planetesimals at the transition between these two steps as well as during their growth at the second step is a matter of debate. It was shown that planetesimal growth requires a very cold disk during all the accretionary epoch at all locations in the disk (Parisi 2013, Planet. Space Sci. 75, 96; and references therein). However, simulations of accretion in the terrestrial and giant planet region show that planetesimals of 10-100 km reach values of their orbital eccentricity which lie at the planetesimal disruption eccentricity limit obtained by Parisi (2013). A key factor in all fragmentation models is the fraction of impact kinetic energy partitioned into kinetic energy of the fragments. The main problem in fragmentation models is that the amount of energy that is dissipated into heat at any collision is unknown. Experimental results suggest that the factor gamma which accounts for the inefficiency of conversion of impact kinetic energy into kinetic energy of the fragments is ~ 0.1. The appropiate choice of gamma=0.1 has been used in calculations of planetary accretion, planetesimal fragmentation, collisional evolution of Kuiper Belt and asteroid belt objects, and in satellite and planetesimal disruption processes (e.g. Parisi 2013). In this work, we explore if planetesimals grow or disrupt at collisions assuming the whole range of possible values of gamma (Arakawa and Higa 1996, Planet. Space Sci. 44, 901) instead of its single value of 0.1.