[P-PS06] 惑星科学

[PPS06-03] Collisional Growth and Fragmentation of Dust Aggregates with Low Mass Ratios

*長谷川 幸彦¹、鈴木 建¹、田中 秀和²、小林 浩³、和田 浩二⁴ (1.東京大学、2.東北大学、3.名古屋大学、4.千葉工業大学)

キーワード：数値計算、惑星形成、原始惑星系円盤

We investigated fundamental processes of collisional sticking and fragmentation of dust aggregates composed of submicron-sized icy dust monomers. We carried out N-body simulations of dust monomers. We examined the condition for collisional growth of two colliding dust aggregates in a wide range of the mass ratio, 1-64. We found that the mass transfer from a larger dust aggregate (called a target) to a smaller one (called a projectile) is a dominant process in collisions with a mass ratio of 2-30 and the impact velocity of about 30-170 m per s. As a result, the critical velocity for collisional fragmentation of the target is considerably reduced for such unequal-mass collisions; the critical fragmentation velocity of collisions with a mass ratio of 3 is about half of that obtained from equal-mass collisions. The impact velocity is generally higher for collisions between dust aggregates with higher mass ratios because of the difference between the radial drift velocities in the typical condition of protoplanetary disks. Therefore, the reduced critical fragmentation velocity for unequal-mass collisions would delay growth of dust grains in the inner region of protoplanetary disks.