The circulation of dust in protoplanetary discs and the initial conditions of planet formation

Abstract

We examine the consequences of a model for the circulation of solids in a protoplanetary nebula in which aerodynamic drag is counterbalanced by the recycling of material to the outer disc by a protostellar outflow or a disc wind. This population of circulating dust eventually becomes unstable to the formation of planetesimals by gravitational instability, and results in the ultimate deposition of ~30-50 M⊕ in planetesimals on scales R<1 au. Such a model may provide an appropriate justification for the approximately power-law initial conditions needed to reproduce observed planetary systems by in situ assembly. © 2014 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.