Granular mechanics simulations of collisions between chondritic aggregates

P Umstatter and HM Urbassek, ASTRONOMY & ASTROPHYSICS, 652, A40 (2021).

DOI: 10.1051/0004-6361/202141581

Context. Collisions of dust aggregates are relevant for the evolution of protoplanetary disks.Aims. While in the past interest focused on aggregates composed of monodisperse grains, here we study the collision of chondritic aggregates, in which - besides a majority of dust grains - larger chondrules are embedded.Methods. We use granular-mechanics simulations to study collisions of chondritic aggregates.Results. Low- velocity collisions lead to pancake-shaped deformations of the fused cluster accompanied by a compaction of the dust grains. Higher collision velocities fragment the aggregates. While some chondrules are almost laid bare after the collision, we find that the largest fragments typically contain chondrules; large fragments thus capture chondrules. Grain compaction is accompanied by an increase in grain - chondrule contacts and is maximum for intermediate velocities, just before aggregates start fragmenting.Conclusions. The presence of chondrules considerably influences the fragmentation behavior of dust aggregates.

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