Activity on the M star of QS Vir

TL;DR

This study analyzes the activity and accretion processes in the binary system QS Vir, revealing stable active regions on the M star and evidence of wind accretion onto the white dwarf through Doppler tomography.

Contribution

It provides detailed phase-resolved spectroscopy and imaging of QS Vir, demonstrating wind accretion and stable active regions on the M star, which advances understanding of magnetic activity and accretion in such binaries.

Findings

Material in the white dwarf's Roche lobe likely from stellar wind accretion.

Two stable active regions identified on the M star.

Hydrogen and Ca II emissions originate mainly from the active M dwarf.

Abstract

We report analysis of VRIJH photometry, and phase-resolved optical spectroscopy of the eclipsing DA white dwarf plus dMe dwarf binary QS Vir. Modeling of the photometric data yields an inclination of $i = 74.9\pm0.6$ and a mass ratio of $q = M_2/M_1 = 0.50\pm0.05$. Our Doppler maps indicate the presence of material in the Roche lobe of the white dwarf, at a location near the M star, likely due to accretion from the stellar wind of the M star (as opposed to Roche-lobe overflow accretion). We also constructed images of the brightness distribution of the M star at different epochs which reveal the location of two stable active regions. Doppler tomography shows that the majority of the Hydrogen and Ca II H&K emission originates on the active M dwarf, likely distributed in two preferred activity longitudes, similar to active regions on BY Dra and FK Comae systems.