The Circumstellar Environments of Young Stars at AU Scales

TL;DR

This review discusses recent infrared interferometry studies revealing the structure, size, and composition of the innermost regions of circumstellar disks around young stars, crucial for understanding planet formation.

Contribution

It summarizes recent advances in interferometric observations that have improved understanding of the inner disk structures and compositions around young stars.

Findings

Inner disk sizes are larger than previously thought.

Disk size correlates with stellar luminosity.

Mineralogy gradients have been observed in disks.

Abstract

We review recent advances in our understanding of the innermost regions of the circumstellar environment around young stars, made possible by the technique of long baseline interferometry at infrared wavelengths. Near-infrared observations directly probe the location of the hottest dust. The characteristic sizes found are much larger than previously thought, and strongly correlate with the luminosity of the central young stars. This relation has motivated in part a new class of models of the inner disk structure. The first mid-infrared observations have probed disk emission over a larger range of scales, and spectrally resolved interferometry has for the first time revealed mineralogy gradients in the disk. These new measurements provide crucial information on the structure and physical properties of young circumstellar disks, as initial conditions for planet formation.