Koji Wada

TL;DR: The Hayabusa2 spacecraft measured the mass, size, shape, density, and spin rate of asteroid Ryugu, showing that it is a porous rubble pile, and observations of Ryugu's shape, mass, and geomorphology suggest that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation.

TL;DR: In this article, a porosity model based on N-body simulations of aggregate collisions is applied to study the porosity change upon collision for a wide range of impact energies. But the authors neglect collisional fragmentation and instead focus on dust evolution outside the snow line, where the fragmentation has been suggested to be less significant than inside the snowline because of the high sticking efficiency of icy particles.

TL;DR: In this article, the authors carried out more than 4000 runs of three-dimensional numerical simulations of collisions between icy equal-mass clusters formed under ballistic particle-cluster aggregation (BPCA), including offset collisions with various values of the impact parameter.

TL;DR: In this paper, the authors proposed a theoretical analysis of the porosity evolution from dust grains via fluffy aggregates to form planetesimals, circumventing the radial drift barrier in planetesimal formation.

TL;DR: In this paper, the authors studied collisions between dust aggregates to construct a model of their structural evolution in protoplanetary disks and carried out three-dimensional simulations of aggregate collisions and examined their compression and disruption processes following their previous two dimensional simulations.