Near Infrared Lines as Diagnostic of Accretion and Winds in
T Tauri Stars
Daniel Folha1,2, Jim Emerson1
1 Physics Department, Queen Mary & Westfield College
Mile End Road, London E1 4NS, United Kingdom
2 Centro de Astrofísica da Universidade do Porto
Rua do campo Alegre 823, P-4150 Porto, Portugal
We present results from a spectroscopic survey of a
sample of T Tauri stars, mostly in the Taurus-Auriga complex. High
resolution spectra (dv~15km s-1) of the observed
stars show that, of the 41 observed in Pa_beta emission, 47% display
red-shifted absorption, while, of the 30 observed in Br_gamma
emission, 27% display red-shifted absorption. The lines are
broad (average FWHM is around 200 km s-1 for both Pa_beta and
Br_gamma) and lack blue-shifted absorption. These observations indicate that
the emission lines form predominantely in infalling material, as
suggested by magnetospheric accretion column models.
Photospheric lines were identified over the observed spectral
ranges in many of the spectra. In these cases we determined the relative
amount of veiling near Pa_beta (J band) and near Br_gamma (K band)
and obtained average values of r_J=0.62+- 0.22 and r_K=1.42+-0.56
for the Classical T Tauri Stars and of r_J=0.14+-0.11 and
r_K=0.0+-0.1$ for the Weak Line T Tauri Stars. No photospheric lines
were identified in 27% of the stars observed at J and in 30% of the
stars observed at K, implying a significant amount of veiling for these
stars. These results show that the veiling at J and K cannot be due
solely to an accretion shock.
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