PHOTOMETRIC VARIABILITY OF SOUTHERN T-TAURI STARS

We present photometric light curves of T Tauri Stars (TTS) observed in the Southern hemisphere. Our list includes 26 TTS, half of which were discovered by the Pico dos Dias survey (PDS). The majority of the obs erved PDS stars are weak TTS and present, on average, the low range of variability typical of such stars. We monitored some of the stars for several seasons in order to detect possible changes in rotational mod ulation. In particular, we find that the classical TTS, AS 216, shows a stable period of 3.12d for three consecutive years (between 1985 and 1987) which then does not reveal itself during the observing season o f 1989 and 1990. Coupled with this change during the last two observin g seasons is an overall increase in the amplitude of the photometric v ariability in all colors. We derive photometric periods for 13 previou sly unmonitored objects, and confirm the previously published rotation al period of SY Cha. In addition, we confirm that TW Cha and SZ 82 do not reveal any signs of periodic modulation.