LAUSR

The orbital period changes of the W UMa-type binary, YY Eri, are analyzed by using all pe and ccd times of light minimum. The results show that its orbital period is undergoing a secular increase superposed on two cyclic oscillations. The continuous increase at the rate of dP/dt = 6.3806 × 10 d yr may be accounted for the mass transfer from the less massive companion to the more massive one. Two periodic variations with the periods of 38.6192 and 22.3573 yr may be attributed to the light-time effect of a faint third star and the cyclic magnetic activity of the system, respectively.