We analyze approximately 100 echelle spectra of the T Tauri star SU Au
r. The photospheric lines appear unveiled and show little variability.
We find evidence for periodic intensity variations in the blue wing o
f H beta between -170 < upsilon < -110 km s(-1) from line center with
a period of approximately 3 days, the rotation period of the star. Bot
h the period and velocity are the same as previously reported for H al
pha in SU Aur. Furthermore, evidence for unsteady accretion is found i
n the presence of a variable red displaced absorption feature with a v
elocity of upsilon similar to +100 km s(-1) in H beta. This feature is
also periodic at 3 days (unlike in H alpha). Several spectra indicate
simultaneous mass inflow and outflow. The Ca II infrared and He I 587
6 fines show modest variability and imply that the structure of the ch
romosphere on SU Aur is very different than solar plage regions. Varia
tions of the Ca II lines and the He I line are well correlated with ea
ch other but only poorly correlated with Balmer line variability. We u
se spherically symmetric radiative transfer codes to calculate the lin
e profiles for SU Aur. The equations of statistical equilibrium are so
lved using the general purpose program CLOUDY. By simultaneously fitti
ng the Balmer lines in SU Aur, we determine to what extent these lines
can be produced in a spherically symmetric wind and constrain the par
ameters of this wind. We find that large turbulent velocities are requ
ired at the base of such a wind, where the bulk of the emission is pro
duced. The steady absorption feature seen at upsilon approximate to -5
0 km s(-1) must form in the outer portions of the stellar wind, implyi
ng a terminal velocity of the wind much below the stellar escape veloc
ity. The mass-loss rate is determined to be about 4.5 x 10(-9) M. yr(-
1).