Cool Stars 14 - Submitted Abstract # 66
This version created on 05 October 2006

He I 10830  as a Probe of Outflow and Accretion in T Tauri Stars


Will Fischer, Univ. of Massachusetts
Suzan Edwards, Smith College
John Kwan, Univ. of Massachusetts
Lynne Hillenbrand, Caltech

He I 10830  is a sensitive probe of outflow and accretion in the
innermost 0.1 AU of classical T Tauri systems.  Because the lower
level of the transition is metastable, profiles readily show
absorption that extends below the one-micron continuum.  In a
Keck/NIRSPEC sample of 38 CTTS, 34 (90%) show such subcontinuum
absorption.  Blueshifted absorption components, present in 70% of the
sample, show evidence for a complex wind-launching scenario, with 30%
of CTTS showing evidence for a disk wind and 40% of CTTS showing
evidence for an accretion-powered stellar wind.  When the He emission
is taken into account, an additional 20% of the profiles indicate a
stellar wind.  The depths and breadths of redshifted subcontinuum
absorption components, found in 50% of the sample, present a challenge
to standard magnetospheric infall models.  Scattering of stellar
photons by a magnetospheric flow aligned with the rotation axis yields
profiles with a maximum red absorption equivalent width of about one
angstrom, less than the red absorption equivalent widths of two-thirds
of the observed profiles.  We explore whether modifications to flow
along aligned dipole field lines can reproduce the depths, velocity
widths, and equivalent widths of the observed He I 10830  red
absorption components.

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