An Investigation of six contact binary systems and a semi-detached one

We present a photometric analysis of six W Ursae Majoris contact binaries and one semi-detached systemusing multifilter CCD observations. The data were obtained with the 0.25 m Schmidt Cassegrain telescope atthe observatory Stazione Astronomica Betelgeuse (SAB) in Magnago, Italy, and the 30-cm Ritchey ChretienAstrograph at the IRIDA observatory (IO) of the NAO Rozhen in Bulgaria. We applied the Wilson-Devinneycode to model the light curves and derive the orbital and physical parameters of the systems. Four of thecontact binaries belong to the W sub-type and two to the A sub-type, and all are in thermal contact. 2MASSJ23194851+3603503 has a very low mass ratio q = 0.093 and a fill-out factor off= 71.4%, whereas theother contact binaries have mass ratios between 0.2 and 0.38 and fill-out factors between 8% and 39%. 2MASSJ04525351+6246069 is a semi-detached system with q = 0.125 and a temperature difference of 540 K betweenthe components. We also estimated the absolute elements of all seven eclipsing binaries.