Observations and light curve solutions of a selection of shallow-contact W UMa binaries

Abstract

Photometric observations in Sloan g′ and i′ bands of the W UMa binaries V0951 Per, CSS J062803.2+571604, CSS J222157.2+275308, CSS J075135.6+382028, V0338 Dra, NSVS 2256852, NSVS 4666412, V1355 Tau, NSVS 4808227, NSVS 4726498, CSS J075350.1+264830 and HL Lyn are presented. The light curve solutions revealed that these binaries have overcontact configurations with small fillout factors (within 0.1–0.2). Seven of them undergo total eclipses and their photometric mass ratios should be accepted with confidence. The temperature differences of the components of CSS J062803.2+571604 and NSVS 2256852 exceed 1100 K which is unusual for overcontact binaries. We suspect that NSVS 2256852 is a probable candidate for merger due to its small mass ratio of q = 0.16 and to the registered decreasing of the orbital period.