The investigation of 84 TESS totally eclipsing contact binaries

TL;DR

This study analyzes 84 totally eclipsing contact binaries using TESS data, classifying their contact levels, studying their physical parameters, and comparing their evolutionary status with historical data.

Contribution

It provides a detailed classification and physical parameter estimation of 84 contact binaries using TESS data, including identification of potential merging candidates and analysis of their evolutionary status.

Findings

18 deep contact binaries identified

43 targets exhibit the O'Connell effect due to star-spots

15 low-mass ratio deep contact binaries may be merging candidates

Abstract

Based on the eclipsing binary catalog provided by \cite{2022ApJS..258...16P}, 84 totally eclipsing contact binaries with stable light curves were selected. The TESS light curves of these 84 targets were studied using the Physics Of Eclipsing Binaries code. The results indicate that there are 18 deep contact binaries, 39 moderate contact binaries, and 27 shallow contact binaries. Among them, 43 targets exhibit the O'Connell effect, which is attributed to the presence of star-spot on the component's surface. 15 targets are low-mass ratio deep contact binaries and may be contact binary merging candidates. Based on the relationship between the period and semi-major axis of contact binaries, their absolute physical parameters such as mass, radius, and luminosity were derived. The evolutionary status of these 84 targets was studied using the mass-luminosity and mass-radius relation diagrams. Their initial masses were also estimated. Our results are compared with those of targets that have been historically studied. Among the 84 targets, 44 targets have been studied before, and 21 of these have mass ratios $q$ that are consistent with historical values within a 10\% difference. For the inconsistent targets, we conducted a detailed investigation and found that the main reasons are poor quality of historical data, or the fact that the machine learning methods used in historical studies might not accurately determine the physical parameters for individual targets.