Short-term Variability in Wolf-Rayet Stars

Abstract

Massive stars play a crucial role in the chemical enrichment of galaxies. These stars exhibit several phenomena including variability of different time scales and extreme mass-loss. Variability of evolved massive stars such as Wolf-Rayet have posed several challenges in our understanding on the origin of variability. Here we present the outcomes of the linear stability analysis in three Wolf-Rayet stars. Linear stability analyses show that the models of these stars have radial modes of the order of a few minutes. When the instabilities in the considered models are followed in the nonlinear regime, substantial inflation in the envelope of these stars are found. Inflated envelope models of the considered stars are showing variability of the order of a few hours which is consistent with observation in two of the considered stars (WR123 & WR 46). In nonlinear regime, shock waves are formed and velocity associated with the outermost grid point of the models are approaching towards the escape velocity in some of the considered models. Our understanding about variability and its possible link with pulsation will help us to probe the interior of the Wolf-Rayet star.