A&A Supplement series, Vol. 128, March II 1998, 561-571
Received June 23; accepted September 1, 1997
,
C.C. Batalha
- G.R. Quast
-
C.A.O. Torres - P.C.R. Pereira
-
M.A.O. Terra - F. Jablonski -
R.P. Schiavon
- J.R. de la Reza
- M.J. Sartori
Send offprint request: Celso Batalha celso@on.br
Observatório Nacional/CNPq/MCT
Rua Gal. José Cristino, 77,
20921-400 Rio de Janeiro, RJ, Brazil
Laboratório Nacional de Astrofısica/CNPq/MCT
Rua Estados Unidos, 154, CP 21,
37500-000 Itajubá, MG, Brazil
Divisão de Astrofísica - INPE/MCT,
CP 515,
12201-970 São José dos Campos, SP, Brazil
Instituto Astronômico e Geofísico - USP,
CP 9638,
01065-970 São Paulo, SP, Brazil
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 observed 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 modulation. 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 of 1989 and 1990. Coupled with this change during the last two observing seasons is an overall increase in the amplitude of the photometric variability in all colors. We derive photometric periods for 13 previously unmonitored objects, and confirm the previously published rotational period of SY Cha. In addition, we confirm that TW Cha and SZ 82 do not reveal any signs of periodic modulation.
keywords: stars: pre-main sequence -- stars: variable