open access

https://hdl.handle.net/2115/34712

Numerical Simulation of Dust Aggregate Collisions

日本語

2008-03-31

北海道大学低温科学研究所

Low Temperature Science

66

55-64

2章 惑星形成と氷微粒子

We study collisions between dust aggregates to construct a model of their structural evolution in protoplanetary disks. We carry out three-dimensional simulations of aggregate collisions and examine their compression and disruption processes. We take clusters of ballistic cluster-cluster aggregation (BCCA) formed by a hit-and-stick process as initial structures and study their head-on collisions with realistic binding forces. Our numerical results indicate that the energy criteria for compression and disruption of BCCA clusters are consistent with previous twodimensional simulations. For aggregate compression due to collision, we succeed in obtaining a scaling law that the gyration radius of the resultant aggregate is proportional to Eimp-0.10, where Eimp is the impact energy. Furthermore, we derive an “equation of state” of aggregates which reproduces the scaling law for compression. This equation of state is useful to describe the density evolution of dust aggregates during their growth. The aggregates are not compressed well by their mutual collisions and the fractal dimension of the compressed aggregates is at most ～2.5. The aggregates composed of ice particles are possible to grow even if the impact velocities are as high as a few tens of m/s. These numerical results suggest that very fluffy planetesimals can be formed in protoplanetary disks by direct collisional growth of dust.

紀要論文

Version of Record

1880-7593