CCD photometric study of the short period contact binary CE Leonis

Light curves and photometric solutions of the contact binary CE Leo are presented in this paper. The light curves appear to exhibit a typical O'Connell effect, with Maximum I being 0.045 mag (V) and 0.048 mag (B) brighter than Maximum II, respectively, and Maximum I shifting to phase 0.26. The new light curve and those published by Samec et al. (1993) show the change in shape of the light curves of the system. From 1989 to 2001, the difference in the depths between the primary and secondary eclipses increased by 0.100 mag (V) and 0.113 mag (B). The orbital period of the system oscillates with a cycle of about 14 years and a semi-amplitude of 0.004 days. The light curves are analyzed by means of the latest version of the Wilson-Devinney code. The results show that CE Leo is a W-subtype contact binary with a ratio $q=0.501$. The asymmetry of the light curves is explained by star spot models. Variations in temperature of the spot on the primary component may be responsible for the light curve variation of the system. The cyclical period change can most probably be attributed to a magnetic activity cycle in the primary component