The Epoch of Giant Planet Migration Planet Search Program. II. A Young Hot Jupiter Candidate around the AB Dor Member HS Psc

We report the discovery of a hot Jupiter candidate orbiting HS Psc, a K7 (≈0.7 M_) member of the ≈130 Myr AB Doradus moving group. Using radial velocities over 4 years from the Habitable-zone Planet Finder spectrograph at the Hobby-Eberly Telescope, we find a periodic signal at Pb = 3.986-0.003+0.044 d. A joint Keplerian and Gaussian process stellar activity model fit to the RVs yields a minimum mass of mₚ sin i = 1.5-0.4+0.6 MJup. The stellar rotation period is well constrained by the Transiting Exoplanet Survey Satellite light curve (Pᵣot = 1.086 ± 0.003 d) and is not an integer harmonic nor alias of the orbital period, supporting the planetary nature of the observed periodicity. HS Psc b joins a small population of young, close-in giant giant planet candidates with robust age and mass constraints and demonstrates that giant planets can either migrate to their close-in orbital separations by 130 Myr or form $in \; situ$. Given its membership in a young moving group, HS Psc represents an excellent target for follow-up observations to further characterize this young hot Jupiter, refine its orbital properties, and search for additional planets in the system.