Spectroscopic and Photometric Study of the Contact Binary BO CVn

TL;DR

This study provides the first spectroscopic mass ratio and detailed physical parameters of the contact binary BO CVn, revealing a high filling factor, significant third light contribution, and ongoing mass transfer from the less to the more massive component.

Contribution

First combined spectroscopic and photometric analysis of BO CVn, determining its mass ratio and physical parameters for the first time.

Findings

High contact configuration with 88% filling factor.

Significant third light contribution of 20-24%.

Mass transfer rate of 6.3×10^-8 M☉/yr from less to more massive star.

Abstract

We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time the latter has been determined for this object. We derived the contact configuration for the system with a very high filling factor of about 88 percent. We were able to reproduce the observed light curve, namely the flat bottom of the secondary minimum, only if a third light has been added into the list of free parameters. The resulting third light contribution is significant, about 20-24 percent, while the absolute parameters of components are: M1=1.16, M2=0.39, R1=1.62 and R2=1.00 (in solar units). The O-C diagram shows an upward parabola which, under the conservative mass transfer assumption, would correspond to a mass transfer rate of dM/dt = 6.3 \times 10-8M\odot/yr, matter being transferred from the less massive component to the more massive one. No cyclic, short-period variations have been found in the O-C diagram (but longer-term variations remain a possibility)