Cyclic flaring activity of flare stars

Methods of detecting probable cycles in the flaring activity of flare stars and determining the cycle durations are examined. A new method of detecting a cycle of flaring activity and determining its duration is proposed assuming periodic flaring activity. This method is applied to two stars from the list of flare stars in the Pleiades cluster, Ton91 and Ton377. Variable flaring activity is found in both stars and the periods are estimated to be P=15.2 and 17.7 years for Ton91 and Ton377, respectively.