# Study of Eclipsing Binary and Multiple Systems in OB Associations V: MQ Cen in Crux OB1

## TL;DR

This study provides detailed spectral and light curve analysis of the massive binary MQ Cen, revealing its physical parameters, distance, and age, and discusses its evolutionary status within the Crux OB1 association.

## Contribution

The paper presents new high-resolution spectral data and multi-band light curve modeling for MQ Cen, determining its physical parameters, distance, and age, and analyzing its evolutionary state.

## Key findings

- Masses and radii of components determined
- Distance to MQ Cen estimated at 2,460 pc
- Age of MQ Cen (~70 Myr) exceeds Crux OB1's (~6 Myr)

## Abstract

The early-type massive binary MQ Cen (P$_{orb}$=3.7 d) has been investigated by means of high-resolution ($R\sim48\,000$) spectral analysis and multi-band (Johnson $BVRI$ and Str\"{o}mgren $vby$) light curve modeling. The physical parameters of the components have been found to be $M_1= 4.26\pm0.10$ M$_{\odot}$, $R_1= 3.72\pm0.05 $R$_{\odot}$, $T_{\rm eff1}=16\,600\pm520$ K, and $M_2= 5.14\pm0.09 $M$_{\odot}$, $R_2= 7.32\pm0.03 $R$_{\odot}$, $T_{\rm eff2}=15\,000\pm500$ K for the primary and secondary, respectively. The orbital inclination is $i=87.0\pm0.2$ deg. The distance to MQ Cen has been derived to be $d=2\,460\pm310$ pc which locates it in the Crux OB1 association. However, the age of MQ~Cen ($\sim70$ Myr) is higher than the one reported for the Crux OB1 association ($\sim$6 Myr). The derived masses are implying a spectral type of B5 for the primary and B4 for the secondary component. Nevertheless, the secondary component, which is more massive, appears to be cooler than the primary component: It has completed its lifetime on the main-sequence and it is now positioned at the turn-off point of the giant branch, meanwhile the less massive primary component is still staying on the main-sequence.