Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy

By S. Edwards, W. Fischer, L. Hillenbrand, J. Kwan. 2006

186 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/57a8d7b151a90d744aa50d9f88d9d00a9734a14d

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In Astronomy and Astrophysics

Citations in the corpus

Accretion-powered Stellar Winds. II. Numerical Solutions for Stellar Wind Torques (2008, background): “In particular, Edwards et al. (2003, 2006) observed the He I 10830 Å line in 39 CTTSs and saw several cases with a broad, deep, blue-shifted absorption, indicating outflow velocities of typically a few hundred, and up to ∼ 400 km s−1.”
ACCRETION RATES FOR T TAURI STARS USING NEARLY SIMULTANEOUS ULTRAVIOLET AND OPTICAL SPECTRA (2013, methodology): “Veilings at 1 µm were found in the literature for a subset of 10 CTTS in this sample (Edwards et al. 2006).”
UV Excess Measures of Accretion onto Young Very Low Mass Stars and Brown Dwarfs (2008, background): “The veiling at even longer wavelengths (e.g., White & Hillenbrand 2004; Edwards et al. 2006) also seems larger than can be explained by the isothermal slab that fits well the Balmer continuum and short-wavelength Paschen continuum.”
Launching of conical winds and axial jets from the disc–magnetosphere boundary: axisymmetric and 3D simulations (2009, background): “At higher accretion rates, there is evidence of a very fast component with v ∼ 200– 400 km s−1 which requires an outflow rate of up to Ṁw ∼ 0.1Ṁd (Edwards et al. 2006; Edwards 2009).”
UNVEILING THE STRUCTURE OF PRE-TRANSITIONAL DISKS (2010, result): “Our results are in agreement with other veiling measurements at 1 µm (Edwards et al. 2006) and 2.2 µm (Folha & Emerson 1999).”
Accretion onto Pre-Main-Sequence Stars (2016, background): “The HeI 10,830-Å profile in this star shows deep (to near-zero residual intensity), broad blueshifted absorption extending to ∼200 km · s−1 (Dupree et al. 2005, 2014; Edwards et al. 2006).”