Abstract We present a comprehensive analysis of 146 contact binaries using medium-resolution Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectra and photometric data from the All-Sky Automated Survey for Supernovae (ASAS-SN) and the Transiting Exoplanet Survey Satellite. Radial velocity curves obtained through the cross-correlation function method were modeled simultaneously with the light curves using the Wilson–Devinney code to derive the physical parameters of these systems. The reliability of our results was verified through comparison with previous studies of 10 systems, showing good agreement. Our analysis shows that the more massive components are generally less-evolved main-sequence stars, whereas the less massive components tend to be oversized and overluminous, consistent with earlier findings. The distribution of orbital angular momentum supports the scenario in which contact binaries form from detached binaries via angular momentum loss. We identified 38 low-mass-ratio ( q < 0.25) systems, 11 of which have extremely low mass ratios ( q < 0.15). A remarkable example is ASASSN-V J111451.48+005038.6, which exhibits a mass ratio of 0.113 and the highest fill-out factor (98.3%) reported to date, making it a strong candidate for future mergers. Conversely, we also identified 11 high-mass-ratio (H-type) systems, including ASASSN-V J093921.74+390452.6—the system with the highest spectroscopically confirmed mass ratio ( q = 0.993) and a low fill-out factor (1.8%), suggesting it recently entered the contact phase. Additionally, several empirical relations between physical parameters are established.
K et al. (2026) studied this question.