Planetesimal Formation by Gravitational Instability of a Porous-Dust Disk

TL;DR

This paper demonstrates that porous icy dust aggregates can become gravitationally unstable in protoplanetary disks, leading to rapid planetesimal formation through gravitational collapse, considering various dynamical effects.

Contribution

It provides a detailed calculation showing how porous dust aggregates evolve and become gravitationally unstable, a novel insight into planetesimal formation mechanisms.

Findings

Porous dust aggregates can become gravitationally unstable.

Gravitational instability leads to rapid planetesimal formation.

The instability occurs under realistic turbulence conditions.

Abstract

Recently it is proposed that porous icy dust aggregates are formed by pairwise accretion of dust aggregates beyond the snowline. We calculate the equilibrium random velocity of porous dust aggregates taking into account mutual gravitational scattering, collisions, gas drag, and turbulent stirring and scattering. We find that the disk of porous dust aggregates becomes gravitationally unstable as they evolve through gravitational compression in the minimum-mass solar nebula model for a reasonable range of turbulence strength, which leads to rapid formation of planetesimals.