Detailed Analysis of Six Contact Binaries and their Possible Origin

A photometric investigation of six binary systems of the W Ursae Majoris (W UMa)-type is presented. We extracted primary and secondary minima from the Transiting Exoplanet Survey Satellite observations of these systems. Using observations previously reported in the literature, linear fits in the O – C diagrams were carried out, and new ephemerides were determined. Light curve solutions were obtained using the legacy version of PHysics Of Eclipsing BinariEs and revealed that five of these systems required cold starspots, implying the presence of the O'Connell effect. The absolute parameters for all of these systems were estimated, and it is shown that they are all consistent with the properties of W UMa-type stars. Finally, we show that the progenitors of these binaries were likely low-mass, short-period, primordial binaries (total mass ≲2 M ⊙ ). We find that mass transfer can be arbitrarily nonconservative and still produce short-period contact binaries. Other formation scenarios are also briefly examined.