Spatially Resolved Molecular Hydrogen Emission in the Inner 200 AU Environments of Classical T Tauri Stars

We present 2.0-2.4 μm integral field spectroscopy at adaptive optics spatial resolution (~0.1'') obtained with the Near-infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory of six classical T Tauri stars: T Tau, DG Tau, XZ Tau, HL Tau, RW Aur, and HV Tau C. In all cases, the v = 1–0 S (1) (2.12 μm) emission is detected at spatially extended distances from the central stars. Moreover, HL Tau, T Tau, RW Aur, and HV Tau C have H 2 that extends to projected distances of more than ~200 AU from the stars. Integrated over the IFU field, most of the H 2 emission is not spatially coincident with the location of continuum flux. Multiple H 2 transitions detected in the K -band spectra show that level populations are typical of gas in thermal equilibrium with excitation temperatures in the 1800-2300 K range. Three of the stars have H 2 velocity profiles that are centered approximately at the stellar radial velocity, and three show velocity shifts with respect to the system. Each of the stars studied here exhibit H 2 morphologies, spatial extents, excitation temperatures, and kinematics that are most consistent with shock-excited emission from the inner regions of the known Herbig-Haro energy flows or from spatially extended wide-angle winds encompassing the outflows rather than predominantly from H 2 stimulated quiescently by UV or X-ray emission from the central stars. The data presented in this study highlights the sensitivity of adaptive-optics-fed integral field spectroscopy for spatially resolving emission line structures in the environments of bright young stars.