Numerical simulation of structure evolution of dust aggregates growing in protoplanetary disks

In protoplanetary disks, dust aggregates grow through mutual collisions, and they would be compressed from a fluffy structure to a relatively compact one. Since the cross section of dust aggregates is changed by the compression, when and how dust aggregates are compressed should be examined to reveal the process of dust growth. In this study, we performed N-body simulations of realistic oblique collisions of aggregates and examine their structure evolution. Applying a compression model based on the numerical simulations of head-on collisions (Suyama et al. 2008) to oblique collisions, we succeeded in the formulation of the evolution of the cross section of aggregates. As a result, the impact compression makes the density of aggregates extremely low. Such aggregates have a large cross section. Therefore, the dust growth process should be reconsidered quantitatively taking into account the model of this study.