Secular Resonances in Planet-Hosting Binary Stars. II. Application to Terrestrial Planet Formation

TL;DR

This study uses numerical simulations to explore how secular and mean-motion resonances influence terrestrial planet formation in binary star systems with giant planets, revealing that mean-motion resonances are dominant in shaping planetary architectures.

Contribution

The paper provides extensive simulation results showing that secular resonances are suppressed and mean-motion resonances drive planet formation in binary systems with giant planets.

Findings

Terrestrial planets typically form as single bodies of 0.6-1.7 Earth masses.

Multiple planets are rare, often Earth-Mars analogs, with the smaller exterior.

Larger giant planet orbits increase the likelihood and mass of multiple planets.

Abstract

Continuing our study of the effects of secular resonances on the formation of terrestrial planets in moderately close binary stars, we present here the results of an extensive numerical simulations of the formation of these objects. Considering a binary with two giant planets and a protoplanetary disk around its primary star, we have simulated the late stage of terrestrial planet formation for different types of the secondary, and different orbital elements of the binary and giant planets. Results demonstrate that terrestrial planet formation can indeed proceed constructively in such systems; however, as predicted by the general theory, secular resonances are suppressed and do not contribute to the formation process. Simulations show that it is in fact the mean-motion resonances of the inner giant planet that drive the dynamics of the protoplanetary disk and the mass and orbital architecture of the final bodies. Simulations also show that in the majority of the cases, the final systems contain only one terrestrial planet with a mass of 0.6-1.7 Earth masses. Multiple planets appear on rare occasions in the form of Earth-Mars analogs with the smaller planet in an exterior orbit. When giant planets are in larger orbits, the number of these double-planet systems increases and their planets become more massive. Results also show that when the orbits of the giant planets carry inclinations, while secular resonances are still suppressed, mean-motion resonances are strongly enhanced, drastically reducing the efficacy of the formation process. We present the results of our simulations and discuss their implications.