Terrestrial Planet Formation in the Presence of Migrating Super-Earths
Résumé
Super-Earths with orbital periods less than 100 days are extremely abundant around Sun-like stars. It is unlikely that these planets formed at their current locations. Rather, they likely formed at large distances from the star and subsequently migrated inward. In this work we use N-body simulations to study the effect of super-Earths on the accretion of rocky planets. In our simulations, one or more super-Earths migrates inward through a disk of Moon-size to Mars-size protoplanetary embryos and much smaller planetesimals embedded in a gaseous disk. In order to qualitatively cover possible scenarios of type-I migration for super-Earths, we have performed simulations considering many different migration speeds and configurations for these bodies. Fast-migrating super-Earths, where super-Earth’s migration is comparable to the traditional type-I isothermal regime (τmig∼0.01-0.1 Myr), only have a modest effect on the protoplanetary embryos and planetesimals. Sufficient material survives to form rocky, Earth-like planets on orbits exterior to the super-Earths'. In contrast, slowly-migrating super-Earths shepherd rocky material interior to their orbits and strongly deplete the terrestrial planet-forming zone. In this situation any Earth-sized planets in the habitable zone are extremely volatile-rich and are therefore probably not Earth-like.