Photometric study of 61 totally eclipsing contact binaries from the ASAS, OGLE, HATNet, AST3 and TESS databases.

Contact binaries form an interesting class of binaries which not only show mutual interactions through gravitationally bound periodic close orbits, but also dynamical interactions through mass transfer, angular momentum loss and modulation of their orbits due to the presence of tertiary components and magnetic activity. They are important as distance indicators and laboratories to study stellar evolutionary models. The current work highlights our photometric study of 61 totally eclipsing contact binaries from the ASAS, OGLE, HATNet, AST3 and TESS databases. Physical parameters are derived using PHOEBE. The selected binaries fall in a range of short periods (0.34-0.97 d), low mass ratios (0.076-0.504), F5-M0 spectral types, and a wide range of fillout factors (3-85%). Based on obtained fillout factors, 5 were classified as shallow/marginal contact, 41 as over-contact and 15 as deep-contact binaries. The absolute parameters are compared with those of well-studied binaries. Possible evolutionary states are discussed.