THERMODYNAMIC EVOLUTION OF PLANETESIMALS IN THE PRIMORDIAL EDGEWORTH

The Kuiper Belt Objects (hereafter KBOs) and cometary nuclei are considered to be among the most primordial objects of the outer solar system. However, 90% of the mass of the Kuiper belt was lost through collisions and ejections by dynamical interactions with Neptune [1-2]. Most of the small bod-ies that have survived in this collisonnal environment have certainly been physically damaged by multiple collisions. Thus, the population of comet-sized objects has been greatly eroded [3]. Cometary nuclei could then be derived from larger parent body [4-5]. Due to the heating generated by collisions during this period, and since they might have experienced some physico-chemical differentiation, the composition of these bod-ies might not reflect that of the primordial planetesim-als. Here, we investigate the post-impact thermochem-ical evolution of comet-size objects and larger parent bodies located in the outer solar system.