Gamma Doradus Pulsations on the Directly Imaged Exoplanet Host Star 51 Eridani

51 Eri is well known for hosting a directly imaged giant planet and for its membership to the β Pictoris moving group. Using data from the Transiting Exoplanet Survey Satellite (TESS), we detect multi-periodic variability on 51 Eri which is consistent with gravity-mode pulsations of Gamma Doradus (γ Dor) stars. Using iterative sine-wave fitting, we identify significant frequencies between ~0–4 cycles/day with amplitudes ranging from ~1–2 mmag. Our results imply that previously reported variability attributed to stellar rotation is likely due to γ Dor pulsations. We conduct a preliminary mode identification of the pulsations and encourage follow up observations and modeling to constrain an independent asteroseismic age of this benchmark exoplanet system.