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