Instabilities in Models of Supergiants MWC 137 and MWC 314
Abstract
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 a 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 30M⊙ to 70M⊙ are unstable while for the case of MWC 314 models with mass below 31M⊙ are unstable. The instabilities have been followed into the nonlinear regime for selected models of these two supergiants. During the nonlinear numerical simulations, instabilities lead to a finite pulsation amplitude with a well defined saturation level in the considered models of MWC 137 with mass greater than 42M⊙. The model of MWC 314 with mass of 40M⊙ - the suggested mass for the primary star - does not show any instabilities both in linear stability analysis and nonlinear numerical simulations. The velocity amplitude reaches to 107 cm s−1 in the nonlinear regime for the model of MWC 314 with mass of 30M⊙. Further extensive numerical simulations and observations are required to understand the origin of the observed variabilities in these stars.