Spatially Resolved Spectroscopy of Sub-AU-Sized Regions of T Tauri and Herbig Ae/Be Disks

TL;DR

This study uses high-resolution near-infrared spectroscopy to spatially resolve and analyze the inner gas and dust regions of disks around young stars, revealing the structure and composition of material close to the star.

Contribution

It provides the first spatially resolved spectroscopic observations of sub-AU regions in T Tauri and Herbig Ae/Be disks, combining high angular and spectral resolution to study gas and dust distributions.

Findings

Inner disk emission size increases with wavelength

Detection of hot hydrogen gas via Brackett-gamma emission

Presence of water vapor and CO gas in inner disks

Abstract

We present spatially resolved near-IR spectroscopic observations of 15 young stars. Using a grism spectrometer behind the Keck Interferometer, we obtained an angular resolution of a few milli-arcseconds and a spectral resolution of 230, enabling probes of both gas and dust in the inner disks surrounding the target stars. We find that the angular size of the near-IR emission typically increases with wavelength, indicating hot, presumably gaseous material within the dust sublimation radius. Our data also clearly indicate Brackett-gamma emission arising from hot hydrogen gas, and suggest the presence of water vapor and carbon monoxide gas in the inner disks of several objects. This gaseous emission is more compact than the dust continuum emission in all cases. We construct simple physical models of the inner disk and fit them to our data to constrain the spatial distribution and temperature of dust and gas emission components.