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Blue large-amplitude pulsators (BLAPs) are a newly discovered type ofvariable star. Their typical pulsation periods are on the order of a few tensof minutes, with relatively large amplitudes of 0.2-0.4 mag in optical bands,and their rates of period changes are on the order of $10^{-7} yr^{-1}$ (bothpositive and negative). They are extremely rare objects and attempts to explaintheir origins and internal structures have attracted a great deal of attention.Previous studies have proposed that BLAPs may be pre-white dwarfs, with massesaround $0.3M_\odot$, or core-helium-burning stars in the range of $\sim0.7-1.1M_\odot$. In this work, we use a number of MESA models to compute andexplore whether BLAPs could be explained as shell helium-burning subdwarfs typeB (SHeB sdBs). The models that best match existing observational constraintshave helium core masses in the range of $\sim 0.45-0.5M_\odot$. Our modelpredicts that the positive rate of period change may evolve to negative. Theformation channels for SHeB sdBs involve binary evolution and although the vastmajority of BLAPs do not appear to be binaries (with the exception of HD133729), the observational constraints are still very poor. Motivated by thesefindings, we explored the Roche lobe overflow channel. Of the 304 binaryevolution models we computed, about half of them are able to produce SHeB sdBsin long-period binaries that evade detection from the limited observations thatare currently available.

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