Photometric variability of blue supergiants: Constraints on stellar masses and evolutionary stages

Abstract

Blue supergiants (BSGs) are crucial to understanding the evolution of massive stars. Although distinguishing between pre- and post-red supergiant (RSG) phases is challenging, stellar pulsations provide valuable constraints on their masses and evolutionary status. This study analyzes TESS light curves of six BSGs with high L/M to identify periodicities. We performed theoretical modeling of the radial unstable modes to characterize the strange modes. We aim to estimate asteroseismic masses, compare them with spectroscopic and evolutionary mass estimates, and assess the evolutionary stage of the stars. We employed the Lomb-Scargle periodogram and the weighted wavelet Z-transform to address quasiperiodic behavior and time-varying signals. A linear nonadiabatic stability analysis was performed to test for radial perturbations, generating eigenfrequencies that enable stellar mass estimation. In addition, we characterized the stochastic low-frequency variability (SLFV). We derive a first guess at the asteroseismic masses. We find that HD 74371 and HD 79186 are evolving blueward following the RSG phase, while the evolutionary stage of HD 115842 cannot be uniquely determined with the available mass estimates. We also find that HD 52382 and HD 99953 are likely in the post-RSG phase; however, their low masses are difficult to reconcile with the available evolutionary models. The extreme supergiant HD 80077 shows the largest mass discrepancy in the sample, suggesting a more complex evolutionary history. The SLFV properties do not provide a clear diagnostic of the evolutionary stage. These results highlight the potential of asteroseismology as a complementary tool for constraining the evolutionary status of BSGs. However, the mass discrepancies found for some objects indicate that additional observational and theoretical efforts are required.