TIO PHOTOMETRY OF 6 T-TAURI STARS

Wing system and UBVRI photometry of six T Tauri stars; RY Tau, T Tau, V410 Tau, SU Aur, RW Aur, and CO Ori, was carried out with the Perkin telescope at Van Vleck Observatory during the 1988/1989 Milky Way season. A TiO sensitive index was formed from two of the Wing system filters. We find that the weak T Tauri star V410 Tau shows enhanced TiO absorption when fainter, in rough quantitative agreement with cool spot models. The large amplitude irregular variables RY Tau, RW Aur, and CO Ori do not show such enhancements. SU Aur and T Tau did not vary sufficiently for us to determine their TiO behavior as a function of brightness. Our data demonstrate that one cannot extend the simple cool spot model, which explains periodic variability in some T Tauri stars, to the irregular variations more typical of classical T Tauri stars such as RY Tau and CO Ori.