The Galaxy's Role in Destabilizing Planets within Wide Binaries

Due to perturbations from passing field stars and the Milky Way's tide, the orbits of many wide (a > 1000 AU) binary stars are driven through very eccentric states. During these high eccentricity (low pericenter) phases, close passages between the binary members can deliver severe gravitational perturbations to planets residing around these stars. We find that this process eventually destabilizes 1/3 to 1/2 of all planetary systems resembling our own when they are embedded within a wide binary. Because of such instabilities, we expect that planetary systems within wide binaries should display an excited eccentricity distribution compared to planets orbiting singleton stars. Indeed, the known exoplanet catalog suggests this is the case. Using numerical simulations that employ a combination of planet-planet scattering as well as perturbations from distant stellar companions, we attempt to explain the eccentricities of known exoplanets within wide binaries