  Hot subdwarf B stars are core-helium burning objects that have undergone
envelope stripping, likely by a binary companion. Using high-speed photometry
from the Transiting Exoplanet Survey Satellite, we have discovered the hot
subdwarf BPM 36430 is a hybrid sdBV_rs pulsator exhibiting several
low-amplitude g-modes and a strong p-mode pulsation. The latter shows a clear,
periodic variation in its pulse arrival times. Fits to this phase oscillation
imply BPM 36430 orbits a barycenter approximately 10 light-seconds away once
every 3.1 d. Using the CHIRON echelle spectrograph on the CTIO 1.5-m telescope,
we confirm the reflex motion by detecting a radial velocity variation with
semi-amplitude, period, and phase in agreement with the pulse timings. We
conclude that a white dwarf companion with minimum mass of 0.42 Msun orbits BPM
36430. Our study represents only the second time a companion orbiting a
pulsating hot subdwarf or white dwarf has been detected from pulse timings and
confirmed with radial velocities.
