Light Curves Analysis and Period Study of Two Eclipsing Binaries UZ Lyr and BR Cyg

TL;DR

This study analyzes light and radial velocity curves of two eclipsing binaries, UZ Lyr and BR Cyg, for the first time simultaneously, revealing new orbital parameters, period behaviors, and stellar features.

Contribution

It presents the first combined analysis of light and radial velocity curves for UZ Lyr and BR Cyg, providing new orbital and physical parameters.

Findings

Periodic behavior of UZ Lyr's O-C curve due to light-time effects.

New orbital period determined for BR Cyg.

Identification of a cool spot on BR Cyg's secondary component.

Abstract

Two eclipsing binary systems UZ Lyr and BR Cyg are the semi-detached types whose secondary component fill its Roche lobe. Although radial velocity and light curves of these systems have already been investigated separately, both radial velocity and light curves of them are analyzed simultaneously for the first time in the present study . Also, the orbital period changes of these systems are studied. Our results show that the mass transfer between components have negligible effects on the orbital period changes of these systems, but two light-time effects are the reasons of the periodic behavior of the O-C curve for UZ Lyr. We could not remark more information about orbital period changes for BR Cyg, but we find a new orbital period for it. By radial velocity and light curves analysis we find a clod spot on the secondary components of BR Cyg. The new geometrical and physical parameters of both systems are obtained and their positions on H-R diagram demonstrated.