On accretion in the polar V379 Vir

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 $M_1=0.61\pm 0.05M_{\odot }$ and its effective temperature to $T_{eff}=10930\pm 350K$. Near-infrared photometry yields a donor radius of $R_2=0.095\pm 0.018R_{\odot }$ and temperature $T_{eff}=1600\pm 180K$. 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.