New Insights into Blue Large-Amplitude Pulsators: Instability Regions and Mass Estimates

Recent research has identified new theoretical instability regions and pulsational masses for blue large-amplitude pulsators (BLAPs), a group of hot pulsating stars whose evolutionary status has been uncertain. The study, conducted by Daniel Jadlovský, Susmita Das, and László Molnár, focuses on two primary mass scenarios for BLAPs: one ranging from 0.3 to 0.4 solar masses and another from 0.7 to 1.1 solar masses. The researchers computed approximately half a million linear BLAP models using the MESA-RSP software and compared the pulsation periods of these models with observed data from BLAP stars.

For the low-mass scenario, the findings indicate that BLAPs occupy a region in the Hertzsprung-Russell diagram where growth rates are positive for the fundamental mode. The model periods align well with observed periods, assuming luminosities around 200 solar luminosities. In contrast, the high-mass scenario suggests that pulsations in the first overtone are more dominant. The study also provides the first seismically constrained mass estimate for the double-mode BLAP star OGLE-BLAP-030, identifying a mass of 0.62 solar masses, which places it between the two mass scenarios.

Additionally, new period relations derived from the models support the low-mass scenario, contributing to a better understanding of the characteristics and behavior of these pulsating stars. The implications of this research extend to the broader field of stellar astrophysics, as it enhances the understanding of the evolutionary processes of hot stars and their pulsational properties. The full paper can be accessed at arXiv:2408.16912.