The first photometric analysis of the overcontact binary MQ UMa with an additional component

TL;DR

This paper presents the first photometric analysis of the overcontact binary MQ UMa, revealing its high fill-out, low mass ratio, potential triple system status, and cyclic period variations, contributing to understanding late-stage binary evolution.

Contribution

It provides the first detailed light curve analysis of MQ UMa, estimates stellar parameters, suggests a tertiary component, and discusses evolution scenarios of similar overcontact binaries.

Findings

MQ UMa is an A-subtype contact binary with high fill-out and low mass ratio.

Evidence suggests MQ UMa may be a triple system with an F5V additional component.

The (O-C) diagram shows cyclic period variation indicating a tertiary companion.

Abstract

The first V Rc Ic bands light curves of MQ UMa are presented and analyzed using the Wilson-Devinney (W-D) program. It is discovered that MQ UMa is an A-subtype contact binary with a high fill-out (f=82 %) and a low mass ratio (q = 0:195), which indicates that it is in the late evolutionary stage of latetype tidal-locked binary stars. The mass of the primary and secondary stars are estimated and the evolutionary status of the two components are placed in the H-R diagram. The W-D solutions also indicates that MQ UMa may be a triple system with an F5V type additional component. A sample of sixteen high fillout, low mass ratio overcontact binaries are collected and their possible evolution scenarios are discussed. Using the five times of light minimum recently observed together with those collected from literatures, the authors find that the observedcalculate (O-C) curve exhibits a cyclic period variation. The cyclic period change also reveals the presence of a tertiary component, which may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.