Which evolutionary status does the Blue Large-Amplitude Pulsators stay at?

TL;DR

This study uses asteroseismology and theoretical modeling to analyze 14 Blue Large-Amplitude Pulsators, suggesting they are mostly core helium burning stars in middle to late helium-burning phases.

Contribution

It provides the first preliminary analysis of BLAPs' evolutionary status using asteroseismology and tailored stellar evolution models.

Findings

BLAPs are likely core helium burning stars.

Most BLAPs are in middle to late helium-burning phases.

Theoretical models support observational data.

Abstract

Asteroseismology is a very useful tool for exploring the stellar interiors and evolutionary status and for determining stellar fundamental parameters, such as stellar mass, radius, surface gravity, and the stellar mean density. In the present work, we use it to preliminarily analyze the 14 new-type pulsating stars: Blue Large-Amplitude Pulsators (BLAPs) which is observed by OGLE project, to roughly analyze their evolutionary status. We adopt the theory of single star evolution and artificially set the mass loss rate of $\dot{M}=-2\times10^{-4}~{\rm M_{\odot}/year}$ and mass loss beginning at the radius of $R=40$ $\rm R_{\odot}$ on red giant branch to generate a series of theoretical models. Based on these theoretical models and the corresponding observations, we find that those BLAP stars are more likely to be the core helium burning stars. Most of them are in the middle and late phase of the helium burning.