Instabilities in models of supergiants MWC 137 and MWC 314

In several B-type supergiants photometric and spectroscopic variabilities together with episodes of enhanced mass-loss have been observed. Here we present the preliminary results of linear stability analysis followed by nonlinear numerical simulations in two B-type supergiants MWC 137 and MWC 314. All the considered models of MWC 137 having mass in the range of 30 M$_{\odot}$ to 70 M$_{\odot}$ are unstable while for the case of MWC 314 models with mass below 31 M$_{\odot}$ are unstable. The instabilities have been followed into nonlinear regime for selected models of these two supergiants. During the nonlinear numerical simulations, instabilities lead to finite amplitude pulsation with a well defined saturation level in the considered models of MWC 137 with mass greater than 42 M$_{\odot}$. The model of MWC 314 with mass of 40 M$_{\odot}$ - the suggested mass for the primary star - does not show any instabilities both in linear stability analysis and nonlinear numerical simulations. Velocity amplitude reaches to 10$^7$ cm/s in the nonlinear regime for the model of MWC 314 with mass of 30 M$_{\odot}$. Further extensive numerical simulations and observations are required to understand the origin of the observed variabilities in these stars.