Abstract
Recent study (Chiang & Goldreich, 1997) implies that the interior of the protoplanetary disk is shadowed from direct exposure to sunlight, so that the H2O ice is prevented from sublimation even at the formation region of terrestrial planets. If planetesimals are formed in such opaque protoplanetary disks, they should be mainly composed of H2O ice. We call such planetesimals icy planetesimals hereafter. The competition of the collisional growth and the sublimation of icy planetesimals controls the abundance of H2O that survives until the formation of protoplanets. In addition, the internal structure and the thermal history of icy planetesimals will have strong effect on the water supply to the planets. In this study, we perform numerical simulation of the thermal history of icy planetesimals heated by short-lived radioactive elements such as 26Al to explorer the condition that allows the formation of hydrous minerals.
