Orbital Stability of Circumstellar Earth-like planets in Binary Systems

Exoplanet searches have uncovered ~100 worlds orbiting one star within a binary system, where significantly more may exist due to observational biases. N-body simulations can identify the stellar binary parameters that allow for stable trajectories and assist in the observations of planetary candidates in stellar binaries. The study by Holman & Wiegert (1999, AJ 117, 621) was limited in scope, where a planet was represented as a massless, coplanar particle. We performed ~700 million simulations that increase the accuracy of the previous result, include massive particles, and allow for a substantial mutual inclination with the binary orbital plane. Using the current population statistics for binary stars, we determined that planets with a semimajor axis less than ~8% of the binary semimajor axis will likely be stable. This estimate decreases in the Lidov-Kozai regime of highly inclined orbits and increases for retrograde orbits to 4% and 10% of the binary semimajor axis, respectively. Our simulation results are also available on GitHub or Zenodo for others to use.