Physical Parameters of 146 Contact Binaries Derived from Light and Radial Velocity Curves

TL;DR

This study analyzes 146 contact binary star systems using combined light and radial velocity data to derive their physical parameters, revealing insights into their formation, evolution, and potential for future mergers.

Contribution

The paper provides the first comprehensive analysis of 146 contact binaries using combined spectroscopic and photometric data, establishing new empirical relations and identifying extreme systems.

Findings

Identified 38 low mass ratio systems, including 11 with extremely low ratios.

Discovered a contact binary with the highest fill-out factor (98.3%) to date.

Confirmed that more massive components are less evolved, supporting angular momentum loss formation scenario.

Abstract

We present a comprehensive analysis of 146 contact binaries using medium-resolution LAMOST spectra and photometric data from the All-Sky Automated Survey for SuperNovae (ASAS-SN) and the Transiting Exoplanet Survey Satellite (TESS). 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 ten 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 over-sized and over-luminous, 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.