OBSERVATIONS AND LIGHT CURVE SOLUTIONS OF SIX DEEP-CONTACT W UMA BINARIES

This work presents photometric observations of the W UMa binaries V0637 Peg. V0473 Cam, CSS J153314.8+560527, CSS J075258.0+382035, V0416 Gem and NSVS 6859986, made using Sloan g ' and i ' filters. The periods of these binaries are in the range of 0.26-0.43 d. The light curve solutions revealed that the components of each binary system are almost equal in temperature. The stellar components are of G and K spectral types and undergo total eclipses. All observation targets have deep-contact configurations with a fill-out factor of f >= 0.5. NSVS 6859986 has one of the highest fill-out factors that have been determined, f = 0.84. We studied the empirical dependencies between the fill-out factor and the stellar parameters (temperature, period, mass ratio, relative component radii, and luminosity ratio) in a sample of around thirty stars; they are consistent with theoretical predictions, although there are deviations from the main tendencies.