A Photometric and Spectroscopic investigation of 11 TESS eclipsing contact binaries

TL;DR

This study combines photometric and spectroscopic data to analyze 11 TESS eclipsing contact binaries, revealing their physical parameters, evolutionary status, and orbital period variations, with implications for binary star evolution.

Contribution

It provides detailed physical parameters and evolutionary insights for 11 contact binaries using combined light and radial velocity curves, including period change analysis.

Findings

Identification of 3 deep, 3 moderate, and 5 shallow contact binaries.

Detection of long-term decreasing and increasing orbital periods in several targets.

Observation of the O'Connell effect and potential merging candidates.

Abstract

By cross-matching the eclipsing binary catalog provided by Prsa et al. (2022) with LAMOST medium resolution spectra, we obtained 11 targets. Combining light and radial velocity curves analysis, we have derived accurate physical parameters for these 11 targets. The results indicate that there are 3 deep contact binaries, 3 moderate ones, and 5 shallow ones. Among them, 3 targets exhibit the O'Connell effect, which is attributed to the presence of star-spot on the component's surface. One target is a low-mass ratio deep contact binary and may be contact binary merging candidates. The evolutionary status of these 11 targets was studied using the mass-luminosity and mass-radius relation diagrams. Based on the O-C (Observed minus Calculated) analysis of 10 targets, we found that the orbital periods of 5 contact binaries show a long-term decreasing trend, likely due to the combined effects of mass transfer between the two components and loss of angular momentum. Meanwhile, the orbital periods of the other 4 stars are continuously increasing, which is attributed to mass transfer. Besides, the O-C curves of 3 targets show clear periodic changes, which might result from the Applegate mechanism or the light travel time effect.