Executive Summary : | subdwarf B (sdB) stars, also known as hot subdwarfs or extended horizontal-branch stars, are helium-core burning stars that have lost most or all of their hydrogen-rich envelopes. Close binaries of these stars with late M dwarf, white dwarf, or brown dwarf partners exhibit distinctive light variations. The formation and evolution of these stars are still unclear in literature, and focused research is needed to understand their formation and evolution. HW Vir binaries, also known as prototype systems, exhibit a strong reflection effect and ellipsoidal modulation or Doppler beaming in hot sdBs with M dwarf or brown dwarf companions. The shape and strength of the reflection effect depend on their orbital inclination, and parameters derived from light curves can constrain system parameters with or without eclipse. studies of HW Vir binaries have revived interest in this type of binary stars, showing large temperature differences between components, short and well-defined primary and secondary eclipses, and a strong reflection effect with deep primary and shallow secondary minimums. These studies will help investigate the formation and evolution of HW Vir-like binary stars. |