SPATIALLY AND SPECTRALLY RESOLVED HYDROGEN GAS WITHIN 0.1 AU OF T TAURI AND HERBIG Ae/Be STARS

Abstract

We present near-infrared observations of T Tauri and Herbig Ae/Be stars with\na spatial resolution of a few milli-arcseconds and a spectral resolution of\n~2000. Our observations spatially resolve gas and dust in the inner regions of\nprotoplanetary disks, and spectrally resolve broad-linewidth emission from the\nBrackett gamma transition of hydrogen gas. We use the technique of\nspectro-astrometry to determine centroids of different velocity components of\nthis gaseous emission at a precision orders of magnitude better than the\nangular resolution. In all sources, we find the gaseous emission to be more\ncompact than or distributed on similar spatial scales to the dust emission. We\nattempt to fit the data with models including both dust and Brackett\ngamma-emitting gas, and we consider both disk and infall/outflow morphologies\nfor the gaseous matter. In most cases where we can distinguish between these\ntwo models, the data show a preference for infall/outflow models. In all cases,\nour data appear consistent with the presence of some gas at stellocentric radii\nof ~0.01 AU. Our findings support the hypothesis that Brackett gamma emission\ngenerally traces magnetospherically driven accretion and/or outflows in young\nstar/disk systems.\n