Possible chromospheric activity cycles in II Peg, UX Ari and V711 Tau

We study the Mount Wilson indices we obtained indirectly from IUE high and low resolution spectra of the RS CVn-type systems II Peg (K2IV), UX Ari (K0IV+G5V) and V711 Tau (K1IV+G5V), extensively observed by IUE from 1978 to 1996. We analyze the activity signatures, which correspond to the primary star, with the Lomb-Scargle periodogram. From the analysis of V711 Tau data, we found a possible chromospheric cycle with a period of 18 years and a shorter ∼3 year cycle, which could be associated to a chromospheric flip-flop cycle. The data of II Peg also suggest a chromospheric cycle of ∼21 years and a flip-flop cycle of ∼9 years. Finally, we obtained a possible chromospheric cycle of ∼6 years for UX Ari.