High-Resolution Spectroscopy Of Ne II Emission From AA Tau And GM Aur

Abstract

We present high-resolution (R = 80,000) spectroscopy of [Ne II] emission from two young stars, GM Aur and AA Tau, which have moderate to high inclinations. The emission from both sources appears centered near the stellar velocity and is broader than the [Ne II] emission measured previously for the face-on disk system TW Hya. These properties are consistent with a disk origin for the [Ne II] emission we detect, with disk rotation (rather than photoevaporation or turbulence in a hot disk atmosphere) playing the dominant role in the origin of the line width. In the non-face-on systems, the [Ne II] emission is narrower than the CO fundamental emission from the same sources. If the widths of both diagnostics are dominated by Keplerian rotation, this suggests that the [Ne II] emission arises from larger disk radii on average than does the CO emission. The equivalent width of the [Ne II] emission we detect is less than that of the spectrally unresolved [Ne II] feature in the Spitzer spectra of the same sources. Variability in the [Ne II] emission or the mid-infrared continuum, a spatially extended [Ne II] component, or a very (spectrally) broad [Ne II] component might account for the difference in the equivalent widths.NSF AST-0607312, AST-0708074NASA/USRA SOFIAGemini ObservatoryNASA NNH07AG51I, NNG04GG92GNASA Astrobiology Institute under Cooperative Agreement CAN-02-OSS-02Life and Planets Astrobiology Center (LAPLACE)6.1 baseAssociation of Universities for Research in Astronomy, Inc.Cooperative agreement with the NSF on behalf of the Gemini partnershipParticle Physics and Astronomy Research Council (United Kingdom)National Research Council (Canada)CONICYT (Chile)Australian Research Council (Australia)CNPq (Brazil)CONICET (Argentina)W.M. Keck FoundationAstronom