Simulated Effects of Radioactive Elements on Magnetic Evolution and Atmospheric Mass Loss of Earth-like Planets

Thousands of exoplanets have been discovered in recent decades, yet Earth remains the only known world with life. To assess the potential habitability of other planets, we must identify the importance of various physical conditions that may contribute to sustaining life. One such factor is the presence of a planetary magnetic field. A planet's magnetic field can protect its atmosphere from photoevaporation, and its long-term strength depends on interior heat flow driven by radiogenic heating from isotopes such as 40K, 232Th, 235U, and 238U. In this work, we use the VPLanet code to simulate the coupled thermal, magnetic, and atmospheric evolution of Earth-like planets with varying radiogenic heat budgets orbiting G-, K-, and M-dwarf stars. The range of isotope abundances tested is based on observed stellar elemental distributions for planet-hosting stars in the Milky Way. We find that variations in radiogenic heating slightly extend dynamo lifetimes and reduces atmosphere and surface water loss for K- and G-dwarf systems, while its effects are more negligible for M dwarfs. Our results show that, while stellar irradiation and planetary location primarily control photoevaporation rates, radiogenic heating contributes to planetary habitability in a small subset of cases and may help refine target selection for future surveys.