Period change of massive binaries from combined photometric and spectroscopic data in Cygnus OB2

TL;DR

This study investigates period variations in seven massive eclipsing binaries in Cygnus OB2 using combined photometric and spectroscopic data, estimating their mass-loss rates and stellar parameters to understand massive star evolution.

Contribution

It introduces a Bayesian method for analyzing period changes in massive binaries and reports the first eclipsing nature of MT059.

Findings

Four binaries show significant period changes.

First detection of eclipsing MT059.

Estimated mass-loss rates for the systems.

Abstract

Context. Mass loss is an important property in evolution models of massive stars. As up to 90% of the massive stars have a visual or spectroscopic companion and many of them exhibit mass exchange, mass-loss rates can be acquired through the period study of massive binaries. Aims. Using our own photometric observations as well as archival data, we look for variations in orbital periods of seven massive eclipsing binary systems in the Cygnus OB2 association and estimate their mass-loss rates and stellar parameters. Methods. We use a Bayesian parameter estimation method to simultaneously fit the period and period change to all available data and a stellar modelling tool to model the binary parameters from photometric and radial-velocity data. Results. Four out of the seven selected binaries show non-zero period change values at two-sigma confidence level. We also report for the first time the eclipsing nature of a star MT059.