FORMATION OF COMETARY SUBNUCLEI

The combined effects of collisions between forming cometary nuclei and the heating and cooling of their interiors in the framework of the st andard model of Solar System (SS) formation are discussed. At the stag e preceding ejection of bodies to the periphery of the SS the interior s of the largest of them probably passed through differentiation. In t he presence of a detectable Al-26 abundance and amorphous ice heating up to the ice melting temperature and partial differentiation of inter iors of the 10 km cometary nuclei are possible just to the end of the collision stage of evolution. Heating and differentiation of large (si milar to 100 km) ice-dust planetesimals can occur even in Kuiper Belt and Oort cloud during the first 10(8) years after their formation. The method is presented for classification of dynamic states and evolutio n tracks on a basis of of ''relations of the order'' made up from char acteristic times of considered processes. Copyright (C) 1996 Elsevier Science Ltd