On the Surface Eruption and Variability in Luminous Blue Variables (LBVs)

Abstract

Luminous blue variables (LBVs) also known as S Doradus variables are evolved massive stars close to the Eddington limit, with a distinct spectroscopic and photometric variability having unsteady mass-loss rates. These stars show a considerable change in their surface temperature from quiescent to outbursts phase. The cause of irregular variability and unsteady mass-loss rate is not properly understood. Here we present the preliminary results of linear stability analysis in six LBVs (GR 290, HD5980, Var 83, MWC 930, W243, R71) during their quiescent and outbursts phase. We note that several modes are unstable in the models of considered LBVs. For the case of one of the LBVs (Var 83), we find the the presence of a monotonic unstable mode with extremely high growth rate for models with surface temperature close to 10000 K.