BVR observations and period variation of the near-contact binary ZZ Aurigae

BVR light curves of ZZ Aurigae were obtained with the 60-cm Cassegrain reflector at the Sobaek Observatory, Korea, between 2000 February and 2001 February. All collected times of minimum light, including our observations, were used for the period study. The period variation could be of quasi-sinusoidal form superposed on an upward parabola. A continuous period increase of  d P /d t =+2.3 × 10⁻⁸ d yr⁻¹  was determined for ZZ Aur. The period of quasi-sinusoidal variation is about ∼26–31 yr. Photometric solutions were found using the Wilson–Devinney method. The Roche configuration of ZZ Aur is that of an Algol-type semidetached system where the primary star nearly fills its Roche lobe and the secondary star fills its lobe. The spot model was used to explain the asymmetry in the light curve known as the O'Connell effect.