2025MNRAS.539.3405M

We collected photometric data from the Transiting Exoplanet Survey Satellite and spectroscopic observations from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. Using this data, we simultaneously analyzed the radial velocity and light curves of four eclipsing contact binaries, i.e. ASAS J061658+1901.2, NSVS 4919378, V589 Lyr, and V1188 Tau, to accurately determine their absolute physical parameters. Based on the eclipse times obtained from the observations of various surveys, we investigated their orbital period variations, finding that the orbital periods of ASAS J061658+1901.2 and NSVS 4919378 decrease and increase continuously, respectively. Additionally, changes in secular period are likely to occur because of mass transfer between the two components; however, the possibility of long-term period changes caused by a third body cannot be excluded. The orbital period of V589 Lyr has remained stable over the past two decades, whereas V1188 Tau has exhibited a cyclic change in its orbital period. This may be attributed to either the light-time effect of a third body or the cyclic magnetic activity of its components. A study of the distribution of total mass, temperature difference, orbital angular momentum, and orbital period suggests that W-subtype contact binaries are more evolved than A-subtype ones.