Tauri Accretion and Outflow with 1 Micron Spectroscopy

In a high dispersion 1 μm survey of 39 classical T Tauri stars veiling is detected in 80%, and He I λ10830 and Pγ line emission in 97% of the stars. On average, the 1 μm 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 Pγ there is a systematic progression in profile morphology with veiling. He I λ10830 has an unprecedented sensitivity to inner winds, showing blueshifted absorption below the continuum in 71% of the CTTS compared to 0% at Pγ. This line is also sensitive to magnetospheric accretion flows, with redshifted absorption below the continuum found in 47% of the CTTS compared to 24% at Pγ. The blueshifted absorption at He I λ10830 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 μm 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 μm continuum by a wind emerging from the inner disk. Both stellar and disk winds are accretion powered since neither is seen in non-accreting WTTS and among the CTTS helium strength correlates with veiling. Five College Astronomy, Smith College, Northampton, MA 10163, [email protected] Five College Astronomy, University of Massachusetts, Amherst, MA, 01003, [email protected], [email protected] Visiting Astronomer, Keck Observatory Guest Observer, Gemini/Keck-NIRSPEC program Dept. of Astronomy, California Institute of Technology, Pasadena, CA 91125, [email protected]