Planetary System Disruption by Galactic Perturbations to Wide Binary Stars

Nearly half of the exoplanets found within binary star systems reside in very wide binaries with average stellar separations beyond 1,000 AU1 (1 AU being the Earth-Sun distance), yet the influence of such distant binary companions on planetary evolution remains largely unstudied. Unlike their tighter counterparts, the stellar orbits of wide binaries continually change under the influence of the Galactic tide and impulses from other passing stars. Here we report numerical simulations demonstrating that the variable nature of wide binary star orbits dramatically reshapes the planetary systems they host, typically Gyrs after for-mation. Contrary to previous understanding, wide binary companions may often strongly perturb planetary systems, triggering planetary ejections and exciting orbital eccentricities of surviving planets. Indeed, observed exoplanet eccen-tricities offer evidence of this; giant exoplanet orbits within wide binaries are statistically more eccentric than those around isolated stars. Both eccentricity 1 a