Shell helium-burning hot subdwarf B stars as candidates for blue large-amplitude pulsators

Blue large-amplitude pulsators (BLAPs) are a newly discovered type of variable star. Their typical pulsation periods on the order few tens minutes, with relatively large amplitudes 0.2–0.4 mag in optical bands, and their rates period changes 10 ?7 yr ?1 (both positive negative). They extremely rare objects attempts to explain origins internal structures have attracted great deal attention. Previous studies proposed that BLAPs may be pre-white dwarfs, masses around 0.3 M ? , or core-helium-burning stars range ?0.7 ? 1.1 . In this work, we use number MESA models compute explore whether could explained as shell helium-burning subdwarfs B (SHeB sdBs). The best match existing observational constraints helium core ?0.45 0.5 Our model predicts rate change evolve negative. formation channels for SHeB sdBs involve binary evolution although vast majority do not appear binaries (with exception HD 133729), still very poor. Motivated by these findings, explored Roche lobe overflow channel. Of 304 computed, about half them able produce long-period evade detection from limited observations currently available.