Phase-Resolved Spectroscopy of the Polar V379 Vir with a Brown Dwarf

TL;DR

This study investigates the orbital and magnetic variability of the polar V379 Vir with a brown dwarf donor, revealing the origin of H-alpha emission and complex magnetic field structures of the white dwarf.

Contribution

It provides the first detailed analysis of orbital spectral variability and magnetic field topology in V379 Vir, utilizing high-resolution spectroscopic data.

Findings

H-alpha emission likely originates in the accretion stream near L1

White dwarf exhibits a complex magnetic field topology

Orbital variability of spectra analyzed for the first time

Abstract

The polar V379 Vir is a well-known magnetic cataclysmic variable with a brown dwarf donor. Despite numerous studies of this system across various spectral ranges, a detailed investigation of the orbital variability of its optical spectra has not been carried out. In this work, we present an analysis of spectroscopic observations of V379 Vir obtained with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The orbital variability of the H$\alpha$ emission indicates that the line is most likely formed in the accretion stream near the Lagrangian point L$_1$, rather than on the donor's surface as previously assumed. The analysis of the rotational variability of the Zeeman splitting of hydrogen lines reveals a complex magnetic field topology of the white dwarf, which differs from a simple dipole configuration.