Erosion driven size-redistribution of protoplanetary disk solids and the onset of streaming Instability and Pebble Accretion

The formation of the first planetesimals and the final growth of planetary cores likely relies on the abundance of small pebbles. The efficiencies of both the streaming instability (SI) process, suggested to catalyze the early growth of planetesimals, and the pebble-accretion process, suggested to accelerate the growth of planetary cores, depend on the sizes of solids residing in the disk. In particular, these processes were found to be sensitive to size-distribution of solids, and efficient planetesimal formation and growth through these channels require a limited pebble size-distribution. Here we show that aeolian-erosion, a process that efficiently grinds down boulders into a mono-sized distribution of pebbles, provides a natural upper cut-off for the maximal pebble sizes. We find the dependence of the critical solids size cut-off on the radial separation, disk age, turbulence strength, and the grain-size composition of the boulders in the disk. This size cut-off shapes the size distribution of small pebbles and thereby helps catalyze the early onset of SI formation of planetesimals, and the later core accretion growth through pebble accretion.