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 AU, 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 Milky Way's 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 their formation. Contrary to previous understanding, a large fraction of very wide binaries may destabilize planetary systems, causing planetary ejections and exciting orbital eccentricities of surviving planets. Indeed, observed eccentricities of giant exoplanets within wide binaries are anomalously high compared to other planetary systems, and binary-triggered disruptions can naturally explain this. This observational signature is reproduced well if we assume isolated stars and wide binaries initially form similar planetary systems that typically extend beyond ~10 AU from their parent stars. Consequently, our results suggest that although wide binaries eventually truncate their planetary systems, most isolated systems of giant exoplanets harbor additional distant, still undetected planets