O-C Analysis of Hot Subdwarf + White Dwarf Binaries Observed by TESS

Hot subdwarf B (sdB) + white dwarf (WD) binaries are compact, post common envelope systems with orbital periods as short as one hour. Their light curves exhibit strong ellipsoidal modulations, Doppler beaming, and even eclipses. Due to the emission of gravitational wave radiation, their orbital periods are expected to decay, and the stars will eventually merge or explode as a Type 1a supernova. Many sdB+WD binaries have predicted gravitational wave strains strong enough to make them useful verification sources for future space missions like LISA. Here we create O-C diagrams for sdB+WD binaries observed by TESS in order to measure their orbital period decay. For systems not showing period changes, we still report ephemerides with the most precise periods and reference times ever published for those systems.