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Published July 20, 2006 | Published
Journal Article Open

Probing T Tauri accretion and outflow with 1 micron spectroscopy


In a high-dispersion 1 μm survey of 39 classical T Tauri stars (CTTSs) veiling is detected in 80% of the stars, and He I λ10830 and Pγ line emission in 97%. 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 CTTSs, 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 CTTSs, 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 nonaccreting WTTSs and among the CTTSs helium strength correlates with veiling.

Additional Information

© 2006 The American Astronomical Society. Received 2006 January 27; accepted 2006 March 29. NASA grant NAG5-12996 issued through the Office of Space Science provides support for this project. Thanks to Andrea Dupree for conversations and collaboration in an earlier phase of this work, to Russel White and Catrina Hamilton for IDL scripts, to the queue observers for the Keck-Gemini NIRSPEC program, Tom Geballe and Marianne Takamiya, for acquiring the 2001 data, and to an anonymous referee for helpful comments.

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