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W. J. Fischer (Univ. of Massachusetts), S. Edwards (Smith College), J. Kwan (Univ. of Massachusetts), L. A. Hillenbrand (CalTech), A. K. Dupree (Harvard-Smithsonian, CfA)
He I \lambda10830 profiles acquired with Keck's NIRSPEC for young low mass stars with high disk accretion rates give a unique new probe of inner winds in disk accretion systems. In some stars, blueshifted absorption penetrates more than 50% into the 1 \mum continuum over velocities ranging from near the stellar rest velocity to the terminal velocity of the wind, unlike inner wind signatures seen in other spectral features. This absorption is formed via resonance scattering and provides the first observational tracer of the wind acceleration region. Since the stellar photosphere is a significant contributor to the continuum at this wavelength, the wind acceleration region must be occulting a large portion of the star. In other stars, the profiles are dominated by emission, providing evidence for the presence of a hot inner wind in some stars, as suggested from an earlier study of He I \lambda5876 profiles.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.