13 New TESS Planets and Homogeneous Properties for 21 Evolved Systems

We present a dedicated transit and radial velocity survey of planets orbiting subgiant stars observed by the TESS Mission. We confirm and characterize 12 new transiting planets and provide updated properties for 9 previously confirmed TESS subgiant systems. We also report the discovery of an outer, non-transiting planet, TOI-1294 c, and three additional stars with long-term RV trends. We find that 19±8% of subgiants in our sample have outer planets, comparable to main-sequence stars. We perform a homogeneous analysis of the stars and planets in the sample, with median uncertainties of 3%, 8% and 15% for planet radii, masses and ages, doubling the number planets orbiting subgiant stars with bulk densities measured to better than 10%. We observe a dearth of giant planets around evolved stars with short orbital periods, consistent with tidal dissipation theories which predict that planets more quickly inspiral as their host stars evolve off the main sequence. We find no correlation between the eccentricity of transiting planets and the age of the system, suggesting a diversity of dissipation efficiencies among the sample. Finally, we find tentative evidence for two distinct hot Jupiter (HJ) populations orbiting our subgiant sample.