Solar-type cycles of the secondary stars in cataclysmic variables

We found cyclical variations in the quiescent magnitudes and outburst inter vals of 21 dwarf novae, 1 nova and 1 nova-like star produced hv the solar-t ype cycles of the? late-type sccondary components. More than 70% of individ ual systems in this work are first studied by Fourier periodogram analysis. It seems that the mean cycle amplitudes of the quiescent magnitudes are co nsiderably larger for SU UMa stars. Cyclical modulations of :quiescent magn itudes found for tile stars, which have orbital periods below the period ga p, support the hypothesis that even almost fully convective secondaries may possess activity cycles. Phe estimated probability density functions show peaks at 9.7, 7.9 and 8.6 yrs for cataclysmic variables (CVs), single main- sequence stars (h:IS) and all stars (CVs+MS), respectively. Using a larger set of data, we confirm that there is no correlation of the cycle period wi th the rotational regime of the secondary star. It is also confirmed that c ycle periods of CVs are in the range of those of single main-sequence stars . We note that the observational cycle parameters (i.e. cycle period, P-cyc , and cycle amplitude of quiescent magnitudes, Deltam) do not seem in relat ion with any other parameter such as masses of primary and secondary stars, mean outburst interval, mean outburst duration, mean decline and rise rate of outbursts, absolute magnitudes in quiescent and outburst states etc.