Photoelectric photometry of very short period eclipsing binary systems and their light curve solutions

New photoelectric observations were made during the nine month period between May 1986 and January 1987 of the very short period eclipsing binary systems V523 Cassiopeiae, TY Bootis, VZ Piscium, AD Cancri, BX Pegasi, and CE Leonis. The facilities of Kitt Peak National Observatory and Lowell Observatory were used on three separate observing runs. The first three respective systems were observed with B and V filters in the standard system. The remaining systems were observed in the newly standardized Cousins system (Bessell, 1976). Light curves with complete phase coverage were obtained for the first four respective systems. The observations of those systems are reported here. All of the light curves appear to be of W Ursae Majoris type. TY Boo is the only system whose light curve was found to be symmetric. Differences in maxima exceeding the probable error of observation are found to be present in the light curves of VZ Psc, AD Cnc and V523 Cas. Rather appreciable differences in eclipse depths, ranging from ;The observations of TY Boo, AD Cnc, V523 Cas and VZ Psc were subjected to synthetic light curve analysis using the Wilson-Devinney Code (Wilson and Devinney, 1971). Several solutions were obtained for each of the first three respective systems, which are all found to be partially eclipsing. Both AD Cnc and V523 Cas were modeled with subluminous regions and the resulting sunspot parameters are reported. A simultaneous modeling of the B, V light curves and the double line radial velocity curves of V523 Cas was performed. Spectroscopic and photometric mass ratios are found to be unequal for both TY Boo and V523 Cas. Absolute parameters were derived for V523 Cas. The Wilson-Devinney code (1984 version) was found incapable of modeling the asymmetric and near ellipsoidal system, VZ Psc. Resulting parameters of the best solutions are tabulated and discussed along with those of other systems which have been modeled similarly. The two competing theories of contact structure are evaluated in the light of the results.