BSN-IV: The First Multiband Light Curve Study of Five W UMa-type Contact Binary Systems

TL;DR

This study provides a comprehensive multiband photometric analysis of five W UMa-type contact binary systems, revealing their orbital period changes, component characteristics, and evolutionary status using new observations and empirical relations.

Contribution

First multiband light curve study of these five systems, including period analysis, component modeling, and evolutionary assessment using the BSN application.

Findings

Two systems show decreasing orbital periods.

Most systems have less than 9.4% temperature contrast.

Identified two systems with extremely low mass ratios.

Abstract

In this work, we present a detailed investigation of five contact binary systems of the W Ursae Majoris (W UMa) type. Multiband photometric observations were conducted using ground-based telescopes in both the northern and southern hemispheres, yielding new times of minima. O-C diagram analysis reveals that two systems exhibit parabolic trends, indicating a gradual long-term decrease in their orbital periods. The light curves were modeled using version 1.0 of the BSN application, with one system requiring the inclusion of a cool starspot to achieve a satisfactory fit. We examined empirical relationships between orbital period and fundamental parameters, identifying the period-semi-major axis (P-a) relation as the most robust correlation, which was used to estimate absolute parameters. To statistically assess thermal equilibrium, we analyzed temperature differences between components and found that 90% of systems exhibit less than 9.4% contrast. Two target systems with extremely low mass ratios were identified, and their orbital stability was evaluated. Based on the effective temperatures and component masses, two systems were classified as W-subtype and three as A-subtype. The evolutionary status of the binaries was assessed through their locations in mass-radius, mass-luminosity, and other empirical diagrams, and initial component masses as well as total mass loss were also estimated.