BSN-V: The First Detailed Light Curve Modeling of Eight Totally Eclipsing Contact Binary Stars Using Ground-Based and TESS Observations

TL;DR

This paper presents detailed light curve modeling of eight totally eclipsing contact binary stars using combined ground-based and TESS data, revealing orbital period trends, stellar parameters, and evolutionary states.

Contribution

It is the first detailed light curve modeling of these eight systems, integrating multiband photometry, TESS data, and orbital analysis to improve understanding of contact binary evolution.

Findings

Orbital period decreases observed in some systems.

Clear separation of systems at P=0.27 days based on period analysis.

Estimated stellar parameters and evolutionary states for all systems.

Abstract

This study broadens our comprehensive investigation of total-eclipse W Ursae Majoris-type contact binaries by analyzing eight additional systems, continuing our previous research. Multiband $BVR_cI_c$ photometric data were obtained at an observatory in Mexico, from which new times of minima were determined. All target systems also had available space-based TESS time-series data. Orbital period variations were studied for eight target systems, showing either linear or parabolic trends. The target systems exhibiting parabolic trends demonstrated a sustained decrease in their orbital periods over time. We modeled the light curves utilizing the PHOEBE Python code in combination with the BSN application. We revisited the relationship between orbital period and the temperature of the hotter component in contact binary systems using an empirical approach. Our analysis identified a clear break at P=0.27 days, separating the systems into two distinct groups for orbital periods shorter than 0.6 days. Following the determination of stellar extinction, absolute parameters for seven systems were estimated employing parallax measurements from Gaia DR3. Based on the components' effective temperatures and masses, the systems were classified into A- and W-subtypes. Their evolutionary states were illustrated using mass-radius and mass-luminosity diagrams.