Physical processes in protoplanetary disks

TL;DR

This review comprehensively covers the physical processes in protoplanetary disks, including their structure, gas and solid physics, instabilities, and large-scale structures, crucial for understanding planet formation.

Contribution

It provides an integrated overview of observational data, theoretical models, and physical mechanisms in protoplanetary disks, highlighting recent insights into disk evolution and structure formation.

Findings

Gas-phase physics explains angular momentum transport via turbulence and winds.

Conditions for gas-particle instabilities are identified.

Large-scale structures like vortices and zonal flows are discussed.

Abstract

This review introduces physical processes in protoplanetary disks relevant to accretion and the initial stages of planet formation. After a brief overview of the observational context, I introduce the elementary theory of disk structure and evolution, review the gas-phase physics of angular momentum transport through turbulence and disk winds, and discuss possible origins for the episodic accretion observed in Young Stellar Objects. Turning to solids, I review the evolution of single particles under aerodynamic forces, and describe the conditions necessary for the development of collective gas-particle instabilities. Observations show that disks can exhibit pronounced large-scale structure, and I discuss the types of structures that may form from gas and particle interactions at ice lines, vortices and zonal flows, prior to the formation of large planetary bodies. I conclude with disk dispersal.