The Dynamical Consequences of a Super-Earth in the Solar System

Abstract

Placing the architecture of the Solar System within the broader context of planetary architectures is one of the primary topics of interest within planetary science. Exoplanet discoveries have revealed a large range of system architectures, many of which differ substantially from the Solar System model. One particular feature of exoplanet demographics is the relative prevalence of super-Earth planets, for which the Solar System lacks a suitable analog, presenting a challenge to modeling their interiors and atmospheres. Here we present the results of a large suite of dynamical simulations that insert a hypothetical planet in the mass range 1-10 $M_\oplus$ within the semi-major axis range 2-4 AU, between the orbits of Mars and Jupiter. We show that, although the system dynamics remain largely unaffected when the additional planet is placed near 3 AU, Mercury experiences substantial instability when the additional planet lies in the range 3.1-4.0 AU, and perturbations to the Martian orbit primarily result when the additional planet lies in the range 2.0-2.7 AU. We further show that, although Jupiter and Saturn experience relatively small orbital perturbations, the angular momentum transferred to the ice giants can result in their ejection from the system at key resonance locations of the additional planet. We discuss the implications of these results for the architecture of the inner and outer solar system planets, and for exoplanetary systems.