Thermal Evolution of TRAPPIST-1 Planets via Multilayer Tidal Dissipation Models

The seven terrestrial planets of TRAPPIST‑1 undergo strong tidal forcing that can dominate their internal heat budgets, yet most studies still adopt homogeneous models. We introduce a self‑consistent multilayer tidal‑dissipation framework that links interior structure, rheology, tidal heating, and long‑term thermal evolution for this system.

Our workflow couples: (i) 1D interior structure profiles that include possible partial molten layers, (ii) multilayer tidal‑dissipation calculations, and (iii) thermal evolution modeling through both a computationally efficient 1D code and a more detailed 2D mantle convection framework (CHIC). Dissipation rates are recomputed at each timestep based on evolving temperature–viscosity profiles, creating a critical feedback loop between heating and cooling processes.

Results demonstrate that tidal heating significantly impacts mantle thermal evolution, with the core-mantle boundary or partial molten regions serving as primary dissipation sources. Under certain conditions, a positive feedback between viscosity drop and increased tidal dissipation triggers runaway melting. Critical factors include initial thermal state, mantle cooling efficiency, and rheological parameters such as reference viscosity and activation energy.

This research advances understanding of tidally-locked exoplanets by demonstrating the importance of incorporating realistic internal structures when modeling thermal evolution, with direct implications for volatile cycling and habitability assessments of the TRAPPIST-1 system.