Terrestrial Planet Formation in the Presence of Migrating Super-earths

TL;DR

This study uses N-body simulations to explore how migrating super-Earths influence the formation of rocky, Earth-like planets, revealing that migration speed critically affects the survival and composition of potential habitable planets.

Contribution

It provides new insights into how different migration speeds of super-Earths impact terrestrial planet formation and the potential habitability of planets in the habitable zone.

Findings

Fast migration allows formation of Earth-like planets outside super-Earths.

Slow migration depletes the terrestrial zone and results in volatile-rich planets.

Migration speed determines the likelihood of forming habitable, Earth-like planets.

Abstract

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. Here 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 planetary embryos and planetesimals embedded in a gaseous disk. We tested a wide range of migration speeds and configurations. Fast-migrating super-Earths ($\tau_{mig} \sim$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.