PHOTOMETRIC ANALYSIS OF ECLIPSING BINARIES: VY UMI, RU UMI AND GSC 04364-00648

We present the photometric analysis of BVR and TESS light curves of three eclipsing binaries, together with their period changes considering archival data and new minima times from our and TESS observations. For the first time we detected wave-like variations with low-amplitude in O − C residua of RU UMi, which can be interpreted as a consequence of the light-time effect caused by the 3rd component with period 7370 days. The period increase detected in the VY UMi system corresponds to mass transfer from the secondary to the primary component. For the GSC 04364-00648 binary system we find quadratic changes on the O − C diagram, which correspond to a period decrease. We cannot make assumptions about their nature, mainly due to short time of observation and uneven coverage of O − C diagram. We also determined the absolute parameter of their components using the photometric solution and GAIA distances.