Next-generation Improvements in Giant-exoplanet Evolutionary and Structural Models

Abstract Many evolutionary models of giant exoplanets still rely on simplifying assumptions that are no longer adequate, given detailed constraints from Jupiter, Saturn, and modern exoplanet observations. Here, we identify the key physical improvements required for next-generation planetary evolution models using our code APPLE , which enables the systematic emulation and extension of legacy studies. We quantify the effects of updated equations of state, helium rain, fuzzy cores, nonadiabatic and compositionally inhomogeneous envelopes, and improved atmospheric boundary conditions, by first isolating the impact of each physical ingredient and then constructing combined baseline models for planets with masses between 0.3 and 4 M Jup , to assess their collective influence on planetary structure and observable properties. We find that the adoption of modern equations of state and realistic heavy-element distributions leads to systematic but sometimes subtle differences (∼5% to 10%) in radius evolution, while helium rain and the treatment of convection can significantly alter thermal histories and atmospheric compositions (by ∼5% to 20%). These updated physical processes must be incorporated into the next-generation exoplanet evolutionary models to achieve physically consistent interpretations of planetary observations.