Astronomy and Astrophysics Supplement Series, Vol. 119, October II 1996, 281-292
Send offprint requests to: G. Cutispoto
Osservatorio Astrofisico di Catania, V.le A.Doria 6,
I-95125 Catania, Italy
Received February 5; accepted March 5, 1996
Abstract:High-precision UBV(RI) photometry of 12 selected active stars, collected at the European Southern Observatory (La Silla, Chile) over the period February - March 1990, is presented. Significant evolution of the light curves, period variations and, in most cases, evidence for long-term variability of the global degree of spottedness are found. Some of the spectral classifications are discussed. This paper is part of a more extensive program focusing on the global properties and evolution of active stars and is aimed at establishing a time-extended photometric database which can give important clues on topics such as the stability of the spotted areas, differential rotation and solar-like cycles.
Key words: stars: activity --- stars: late-type --- stars: variables