| Abstract |
Rapid orbital drift of macroscopic dust particles is one of the major obstacles against planetesimal formation in proto-planetary disks. We reexamine this problem by considering porosity evolution of dust aggregates. We show that dust particles can evolve into highly porous aggregates (with internal densities of much less than 0.1 g/cc) even if collisional compression is taken into account. Furthermore, we find that the high porosity triggers significant acceleration in collisional growth. Thanks to this rapid growth, the highly porous aggregates are found to overcome the radial drift barrier at distances less than 10 AU from the central star. This suggests that, if collisional fragmentation is truly insignificant, formation of icy planetesimals is possible via direct collisional growth of submicron-sized icy particles. |
