Protoplanetary Disks and Their Evolution

TL;DR

Protoplanetary disks are common around young stars, evolving over millions of years through processes like accretion, outflows, and planetesimal formation, which are studied mainly via infrared and millimeter observations to understand planet formation.

Contribution

This review synthesizes recent infrared and millimeter observations of protoplanetary disks, highlighting their properties and evolutionary pathways beyond 1 AU.

Findings

Disks are prevalent around young stars and persist for several million years.

Infrared and millimeter observations reveal disk mass, size, and structure.

Disks evolve through accretion, outflows, and planetesimal formation.

Abstract

Flattened, rotating disks of cool dust and gas extending for tens to hundreds of AU are found around almost all low mass stars shortly after their birth. These disks generally persist for several Myr, during which time some material accretes onto the star, some is lost through outflows and photoevaporation, and some condenses into centimeter- and larger-sized bodies or planetesimals. Through observations mainly at infrared through millimeter wavelengths, we can determine how common disks are at different ages, measure basic properties including mass, size, structure, and composition, and follow their varied evolutionary pathways. In this way, we see the first steps toward exoplanet formation and learn about the origins of the Solar System. This review addresses observations of the outer parts, beyond 1 AU, of protoplanetary disks with a focus on recent infrared and (sub-)millimeter results and an eye to the promise of new facilities in the immediate future.