Planet Migration in Turbulent or Windy Discs

This thesis investigates the migration dynamics of planets in turbulent protoplanetary discs, focusing particularly on the impacts of disc turbulence, and magnetohydrodynamics (MHD) disc winds on planetary orbital evolution and observational signatures. Using advanced hydrodynamical simulations with the FARGO and FARGO3D code, I explore how stochastic turbulent perturbations influence planetary mean-motion resonances (MMRs). I find that turbulence enhances resonance overstability, increasing equilibrium eccentricities and driving planet pairs to sequentially break from lower-order resonances (e.g., 3:2, 4:3) and temporarily stabilise in tighter resonances (e.g., 5:4). In parallel, I investigate the influence of magnetically driven disc winds on planet migration in protoplanetary discs (PPDs). My simulations reveal that MHD disc winds can significantly reduce or reverse inward migration rates of planets, effectively addressing the “migration braking” problem observed in planet formation theories. Additionally, my work addresses a critical methodological issue in numerical simulations of planet-disc interactions. Traditional simulations often fix planets at specific orbits to induce observable disc structures like gaps and rings. However, my findings show that migrating planets produce similar substructures but require notably different disc conditions and parameters compared to fixed planets. This discrepancy implies that the observational interpretation of disc substructures must account for the realistic migration of embedded planets. And my work also show that combined constraints from planet migration and dust dynamics can be used to put tight constraints on the unobservable gas masses of PPDs. Together, these studies provide new insights into the complex interplay between planet migration, turbulence, and MHD disc winds, significantly impacting our understanding of planet formation and the interpretation of observed disc features.