Probing T Tauri accretion and outflow with 1 micron spectroscopy

In a high-dispersion 1 mu m survey of 39 classical T Tauri stars ( CTTSs) veiling is detected in 80% of the stars, and He I lambda 10830 and P gamma line emission in 97%. On average, the 1 mu m veiling exceeds the level expected from previously identified sources of excess emission, suggesting the presence of an additional contributor to accretion luminosity in the star-disk interface region. Strengths of both lines correlate with veiling, and at P gamma there is a systematic progression in profile morphology with veiling. He I lambda 10830 has an unprecedented sensitivity to inner winds, showing blueshifted absorption below the continuum in 71% of the CTTSs, compared to 0% at P gamma. This line is also sensitive to magnetospheric accretion flows, with redshifted absorption below the continuum found in 47% of the CTTSs, compared to 24% at P gamma. The blueshifted absorption at He I lambda 10830 shows considerable diversity in its breadth and penetration depth into the continuum, indicating that a range of inner wind conditions exist in accreting stars. We interpret the broadest and deepest blue absorptions as formed from scattering of the 1 mu m continuum by outflowing gas whose full acceleration region envelopes the star, suggesting radial outflow from the star. In contrast, narrow blue absorption with a range of radial velocities more likely arises via scattering of the 1 mu m continuum by a wind emerging from the inner disk. Both stellar and disk winds are accretion powered, since neither is seen in nonaccreting WTTSs and among the CTTSs helium strength correlates with veiling.