Abstract:
B[e] type stars are characterized by strong emission lines, photometric, and spectroscopic variabilities and unsteady mass-loss
rates. MWC 137 is a galactic B[e] type star situated in the constellation Orion. Recent photometric observation of MWC 137 by
TESS has revealed variabilities with a dominant period of 1.9 d. The origin of this variability is not known but suspected to be
from stellar pulsation. To understand the nature and origin of this variability, we have constructed three different set of models
of MWC 137 and performed non-adiabatic linear stability analysis. Several low order modes are found to be unstable in which
models having mass in the range of 31–34 M and 43–46 M have period close to 1.9 d. The evolution of instabilities in the
non-linear regime for model having solar chemical composition and mass of 45 M leads to finite amplitude pulsation with a
period of 1.9 d. Therefore, in the present study we confirm that this variability in MWC 137 is due to pulsation. Evolutionary
tracks passing through the location of MWC 137 in the Hertzsprung–Russell diagram indicate that the star is either in post main
sequence evolutionary phase or about to enter in this evolutionary phase.
