Determining the impact of post-main-sequence stellar evolution on the transiting giant planet population

Abstract

The post-main sequence evolution of stars is expected to impact the exoplanets residing on close-in orbits around them. Using photometric data from the TESS Full-Frame-Images we have performed a transit search for exoplanets with post-main sequence hosts to search for the imprints of these impacts on the giant planet population. We detect 130 short period planets and candidates, thirty-three of which are newly discovered candidates, from a sample of 456,941 post-main sequence stars spanning the evolutionary stages from the end of the main sequence to the bottom of the red giant branch. We measure an occurrence rate of $0.28 \pm 0.04$% for short period giant planets orbiting post-main sequence stars. We also measure occurrence rates for two stellar sub-populations, measuring values of $0.35 \pm 0.05$% for a sub-population representing the earliest stages of post-main sequence evolution and $0.11^{+0.06}_{-0.05}$% for a sub-population of more evolved stars. We show that the giant planet occurrence rate decreases with increasing stellar evolution stage, with a larger occurrence rate decrease observed for shorter period planets. Our results are clear evidence that the population of short period giant planets is being sculpted by the post-main sequence evolution of the host stars, and we conclude that this is most likely through the destruction of these giant planets through the increased strength of planet-star tidal interactions resulting in the rapid tidal decay of the planets' orbits.