Rocky Planetesimal Formation via Fluffy Aggregates of Nanograins

TL;DR

This paper proposes a new model for rocky planetesimal formation where nanometer-sized silicate grains, produced by evaporation and recondensation in the early solar nebula, aggregate directly into planetesimals.

Contribution

It introduces a novel scenario where nanograins form and grow into planetesimals without fragmentation or significant radial drift, advancing understanding of early solar system formation.

Findings

Nanograins can grow into planetesimals via direct aggregation.

The model avoids catastrophic fragmentation and radial drift issues.

Conditions for protoplanet formation are identified.

Abstract

Several pieces of evidence suggest that silicate grains in primitive meteorites are not interstellar grains but condensates formed in the early solar system. Moreover, the size distribution of matrix grains in chondrites implies that these condensates might be formed as nanometer-sized grains. Therefore, we propose a novel scenario for rocky planetesimal formation in which nanometer-sized silicate grains are produced by evaporation and recondensation events in early solar nebula, and rocky planetesimals are formed via aggregation of these nanograins. We reveal that silicate nanograins can grow into rocky planetesimals via direct aggregation without catastrophic fragmentation and serious radial drift, and our results provide a suitable condition for protoplanet formation in our solar system.