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Published December 10, 2003 | Published
Journal Article Open

He I λ10830 as a probe of winds in accreting young stars


He I λ10830 profiles acquired with Keck's NIRSPEC for six young low-mass stars with high disk accretion rates (AS 353A, DG Tau, DL Tau, DR Tau, HL Tau, and SVS 13) provide new insight into accretion-driven winds. In four of the stars, the profiles have the signature of resonance scattering, and they possess a deep and broad blueshifted absorption that penetrates more than 50% into the 1 μm continuum over a continuous range of velocities from near the stellar rest velocity to the terminal velocity of the wind, unlike inner wind signatures seen in other spectral features. This deep and broad absorption provides the first observational tracer of the acceleration region of the inner wind and suggests that this acceleration region is situated such that it occults a significant portion of the stellar disk. The remaining two stars also have blue absorption extending below the continuum, although here the profiles are dominated by emission, requiring an additional source of helium excitation beyond resonant scattering. This is likely the same process that produces the emission profiles seen at He I 5876 Å.

Additional Information

© 2003 The American Astronomical Society. Received 2003 July 21; accepted 2003 October 30; published 2003 November 14. Heartfelt thanks to an anonymous referee who spurred significant improvements in the manuscript and a deep mahalo to the queue observers for the Keck-Gemini NIRSPEC program, Tom Geballe and Marianne Takamiya for the 2001 data. NASA grant NAG5-12996 issued through the Office of Space Science provides support for this project.

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