2004MNRAS.347..307Z

We present a long-term photoelectric and charge-coupled device (CCD) photometric study of the short-period W UMa star V523 Cas made from 1986 to 2000. The orbital-period changes and light-curve variations of the binary system are studied. 47 new times of minima are obtained from our data. A period study covering more than 43 000 cycles based on the photoelectric and CCD photometric times of minima confirms the long-term, secular period changes of the system. It is found that the orbital period has been continuously increasing in the past three decades at a rate of dP/dt 8.84x10^–8 d/yr. No cyclic period variations are found from our result. Eight V and five B completely covered light curves are formed from the observations made in eight epochs. The light curves are of W UMa type and show marked asymmetries with unequal maxima. The differences between the two maxima in each light curve appear to be cyclic over a time-scale of about 8 yr. Based on a one-spot model, the light curves are analysed with the Wilson-Devinney code. The photometric solutions reveal a W-subtype, contact configuration for V523 Cas. The photometric mass ratio is found to be 0.51, and the masses and radii for the components are deduced as 0.75±0.03 M_☉, 0.74±0.04 R_☉for the primary and 0.38±0.02 M_☉, 0.55±0.02 R_☉for the secondary, respectively. We discuss the evolutionary status of the system as well as the possible spot activity along with the mass transfer among the components.