Magnetodynamo lifetimes for rocky, Earth‐mass exoplanets with contrasting mantle convection regimes

摘要: [1] We used a thermal model of an iron core to calculate magnetodynamo evolution in Earth-mass rocky planets determine the sensitivity dynamo lifetime and intensity with different mantle tectonic regimes, surface temperatures, properties. The heat flow at core-mantle boundary (CMB) is derived from numerical models convection viscous/pseudoplastic rheology that captures phenomenology plate-like tectonics. Our predict long-lived (~8 Gyr) field for Earth similar exoplanets plate Both elevated temperature pressure-dependent viscosity reduce CMB but produce only slightly longer-lived dynamos (~8–9.5 Gyr). Single-plate (“stagnant lid”) relatively low (~10.5 Gyr) dynamos. These weaker can cease several billions years subsequently reactivate due additional entropy production associated inner growth, possible explanation absence magnetic on present-day Venus. We also show operation sensitive initial temperature, size, solidus planet's core. dependencies would severely challenge any attempt distinguish tectonics stagnant lids based presence or field.