Work

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

Year: 2026

Type: article

Abstract: Blue supergiants are crucial to understanding the evolution of massive stars. However, their formation, mass loss, and pulsational properties remain poorly understood. 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 blue supergiants with high luminosity-to-mass ratios 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). Using linear nonadiabatic pulsation models, we derive a first guess at the asteroseismic masses. We find that and are evolving blueward following the RSG phase with masses of 7.3 M_⊙ and 10.7 M_⊙, respectively, while the evolutionary stage of (with 20.1 M_⊙) cannot be uniquely determined with the available mass estimates. We also find that (either 3.9 M_⊙ or 6.1 M_⊙) and (3.8 M_⊙) are likely in the post-RSG phase; however, their low masses are difficult to reconcile with the available evolutionary models. The extreme supergiant , with 132.7 M_⊙, 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. However, we find a bimodal distribution of the power-law slopes and characteristic timescales. HD 74371 HD 79186 HD 115842 HD 52382 HD 99953 HD 80077 These results highlight the potential of asteroseismology as a complementary tool for constraining the evolutionary status of B-type supergiants. However, the mass discrepancies found for some objects indicate that additional observational and theoretical efforts are required.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202661946