Planetary Migration in Resonance, the question of the Eccentricities : Les Houches contribution

TL;DR

This paper investigates how planetary migration and damping mechanisms influence the eccentricities of resonant exoplanet pairs, demonstrating that the inner disk can effectively damp eccentricities, aligning simulations with observations.

Contribution

It shows that the inner disk can provide the necessary eccentricity damping during planetary migration, supported by hydrodynamical simulations of the GJ 876 system.

Findings

Inner disk damping can match observed eccentricities.

Hydrodynamical simulations reproduce GJ 876's orbital elements.

Eccentricity growth can be controlled by disk interactions.

Abstract

The formation of resonant planets pairs in exoplanetary systems involves planetary migration inside the protoplanetary disc : an inwards migrating outer planet captures in Mean Motion Resonance an inner planet. During the migration of the resonant pair of planets, the eccentricities are expected to rise excessively, if no damping mechanism is applied on the inner planet. We express the required damping action to match the observations, and we show that the inner disk can play this role. This result applies for instance to the system GJ 876 : we reproduce the observed orbital elements through a fully hydrodynamical simulation of the evolution of the resonant planets.