The Dominant Role of Secular Resonance in Shaping Planetary Architecture, Stability, and the Origin of Interstellar Objects

Giant planets are fundamental to the dynamical evolution of planetary systems. In our solar system, Jupiter and Saturn act as key architects in shaping the asteroid belt and promoting terrestrial planet formation. Among extrasolar planets many similar systems exist such as the system of GJ 876 where three cold giants created an empty inner region analogous to our asteroid belt while driving a super-Earth into a 2-day orbit. To identify the specific mechanisms through which giant planets affect their systems, we performed over 1,200 numerical simulations of planet formation across diverse protoplanetary disks. We found that secular resonances induced by giant planets are, by far, the most dominant factors in the subsequent formation, long-term stability, and final architecture of their systems. For instance, in our solar system, it is the secular resonance of Saturn that limits our terrestrial planets to within 1.9 (au) and inhibits the formation of super-Earths. In contrast, in GJ 876 system, a super-Earth did in fact form, but it was the sweeping secular resonances due to the migration of giant planets that created the system’s asteroid belt-analog and caused the inward scattering of the super-Earth into its close-in and stable orbit. Furthermore, our results demonstrate that secular resonances are crucial to the scattering of planetesimals to large distances, especially during the formation of planets. These scattered bodies are the primary sources of the exo-Oort cloud comets and serve as the origin of the interstellar objects. In this talk, we present a detailed analysis of these implications and highlight how secular resonances dictate system architecture and stability, and also drive the formation of interstellar bodies.