| Abstract : | Photometric and spectroscopic variabilities have been observed in several stars including B-type supergiants. Recent ground and space-based observations have revealed variabilities of the order of a few hours to several days in these stars. High-quality photometric data from KEPLER and TESS have revolutionized our understanding of variabilities in stars. Decades ago, radial and non-radial pulsations have been proposed as one of the underlying causes of such variabilities in massive stars. However, interpretation of these observed variabilities in terms of stellar pulsation requires a detailed modelling of stars and associated pulsation frequencies. Here we present a case study for three B-type stars – κ Cassiopeiae, HD 50064 and MWC 137. We have constructed models of these stars using observed surface temperature, luminosity and chemical composition. Linear stability analyses in models of these stars have been performed to identify excited modes of unstable models. Low order radial and non-radial modes are unstable in the considered models of these stars. In order to find the final fate of unstable models, dense grid non-linear numerical simulations have been carried out. Predictions of the numerical simulation agree with the observed variabilities of 2.7 days and 1.9 days for κ Cassiopeiae and MWC 137, respectively. However, we are unable to explain the dominant variability of 37 days observed in HD 50064 which motivates us to consider the effect of rotation, time-dependent convection and more realistic models of HD 50064 in the future. |
