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Published August 1, 2010 | Published
Journal Article Open

Spatially and Spectrally Resolved Hydrogen Gas within 0.1 AU of T Tauri and Herbig Ae/Be Stars


We present near-infrared observations of T Tauri and Herbig Ae/Be stars with a spatial resolution of a few milliarcseconds and a spectral resolution of ~2000. Our observations spatially resolve gas and dust in the inner regions of protoplanetary disks, and spectrally resolve broad-linewidth emission from the Brγ transition of hydrogen gas. We use the technique of spectro-astrometry to determine centroids of different velocity components of this gaseous emission at a precision orders of magnitude better than the angular resolution. In all sources, we find the gaseous emission to be more compact than or distributed on similar spatial scales to the dust emission. We attempt to fit the data with models including both dust and Brγ-emitting gas, and we consider both disk and infall/outflow morphologies for the gaseous matter. In most cases where we can distinguish between these two models, the data show a preference for infall/outflow models. In all cases, our data appear consistent with the presence of some gas at stellocentric radii of ~0.01 AU. Our findings support the hypothesis that Brγ emission generally traces magnetospherically driven accretion and/or outflows in young star/disk systems.

Additional Information

© 2010 The American Astronomical Society. Received 2010 May 13; accepted 2010 May 31; published 2010 July 6. Data presented herein were obtained at the W. M. Keck Observatory, from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The ASTRA program, which enabled the observations presented here, was made possible by funding from the NSF MRI grant AST-0619965. This work has used software from NExSci at the California Institute of Technology. The Keck Interferometer is funded by the National Aeronautics and Space Administration as part of its Exoplanet Exploration program. J.R.G. was supported in part by the University of California Lab Research Program 09-LR-01-118057-GRAJ and NSF AST-0909188.

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