In a high dispersion 1 micron survey of 39 classical T Tauri stars veiling is detected in 80%, and He I 10830 and Pgamma line emission in 97% of the stars. On average, the 1 micron 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 Pgamma there is a systematic progression in profile morphology with veiling. He I 10830 has an unprecedented sensitivity to inner winds, showing blueshifted absorption below the continuum in 71% of the CTTS compared to 0% at pgamma. 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 Pgamma. The blueshifted absorption at 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 micron 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 micron 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.Comment: 55 pages, including 16 figures. Astrophysical Journal, accepte

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High-resolution emission-line proÐles of He I and He II in 31 classical T Tauri stars are analyzed with the aim of probing the environs of the star-disk interface in accreting low-mass young stars. The diagnostic power of the helium lines lies in their high-excitation potentials, which restrict their formation to a region either of high temperature or close proximity to a source of ionizing radiation. The He I proÐles are decomposed into kinematic components that support the paradigm of magnetically controlled accretion from the disk onto the stellar surface but also require a signiÐcant contribution from a hot wind. A narrow component, seen in 28/31 stars, is characterized by relatively uniform line widths and centroid velocities among all the helium lines. Our analysis supports previous conclusions that this feature is consistent with formation in the decelerating postshock gas at the magnetosphere footpoint. A broad component, seen in 22/31 stars, displays a diversity of kinematic properties. Our analysis suggests that in many stars the He I broad component is itself composite. At one extreme are stars where the broad component is redshifted in excess of 8 km s~1, as would occur if helium emission arises primarily from polar angles less than in the funnel Ñow. At the other extreme are stars where the broad component 54¡ .7 is blueshifted in excess of [30 km s~1, requiring an origin in outÑowing gas. The additional occurrence of maximum blue wing velocities exceeding [200 km s~1 in 14 stars leads us to argue that hot winds are present in about half of our sample. The relation between the narrow component and the optical veiling di †ers between the stars with or without a hot helium wind, suggesting that when the hot wind is present the luminosity and temperature of the accretion shock are reduced. A comparison of broad component helium emission with standard outÑow indicators leads us to suggest that there are two sources of inner wind in T Tauri accretion disk systems : one a hot polar/coronal wind that prevails in stars with high veiling, and the other a more widespread cool disk wind that is likely launched at the magnetosphere/disk boundary.

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