Tidal locking as a negative feedback on Earth-like planetarydynamos: consequences for magnetic shielding and habitability

In this poster, we investigate how tidal locking affects the planetary dynamo and the magnetospheres of Earth-like planets orbiting the habitable zones of M dwarfs. We couple an empirical stellar wind model with two distinct planetary dynamo paradigms, direct rotational scaling and energy-flux scaling, using a Constant Time Lag (CTL) model to simulate continuous tidal spin-down until synchronization. We model two hypothetical planets based on a highly dissipative Modern Earth and a less dissipative Early Earth during the Paleoarchean. Our results show that tidal locking acts as a severe negative feedback on planetary magnetism across both paradigms, where the dipolar field frequently collapses before full tidal synchronization is reached. Essentially, a shielded atmospheric environment around M dwarfs requires a host massive enough (≥ 0.32 M_) to place the HZ at wider orbital distances, sparing the planet from extreme stellar wind pressures, and the internal tidal dissipation of the planet must be sufficiently low to prevent rapid rotational decay.