On accretion in the polar V379 Vir

TL;DR

This study analyzes 20 years of optical and infrared data of the polar V379 Vir with a brown dwarf secondary, constraining system parameters and accretion rate, revealing a higher-than-expected mass transfer rate.

Contribution

It provides detailed modeling of the spectral energy distribution and cyclotron emission, offering new constraints on the system's physical parameters and accretion processes.

Findings

White dwarf mass estimated at 0.61 solar masses

Donor radius and temperature constrained

Accretion rate found to be higher than wind-driven expectations

Abstract

Based on optical and infrared survey data spanning $\approx 20$ years of observations, the long-term variability of the polar V379 Vir with a brown dwarf secondary has been studied. By modeling the spectral energy distribution, we constrain the white dwarf's mass to $M_1 = 0.61 \pm 0.05~M_{\odot}$ and its effective temperature to $T_{eff} = 10930 \pm 350~K$. Near-infrared photometry yields a donor radius of $R_2 = 0.095 \pm 0.018 R_{\odot}$ and temperature $T_{eff} = 1600 \pm 180 K$. Modeling of the cyclotron emission from the accretion spot, detected with the Spitzer infrared telescope, gives an accretion rate of $\dot{M} \approx 3 \times 10^{-13} M_{\odot}/yr$. This rate is consistent with polars in a low accretion state, but significantly higher than expected from wind-driven mass transfer.