  The stable oscillations of pulsating stars can serve as accurate timepieces,
which may be monitored for the influence of exoplanets. An external companion
gravitationally tugs the host star, causing periodic changes in pulsation
arrival times. This method is most sensitive to detecting substellar companions
around the hottest pulsating stars, especially compact remnants like white
dwarfs and hot subdwarfs, as well as delta Scuti variables (A stars). However,
it is applicable to any pulsating star with sufficiently stable oscillations.
Care must be taken to ensure that the changes in pulsation arrival times are
not caused by intrinsic stellar variability; an external, light-travel-time
effect from an exoplanet identically affects all pulsation modes. With more
long-baseline photometric campaigns coming online, this method is yielding new
detections of substellar companions.
