Abstract:The Kepler mission has discovered that close-in super-Earth planets are common around solar type stars. They are often seen together in multiplanetary systems, but their period ratios do not show strong pile-ups near mean motion resonances (MMRs). One scenario is that super-Earths form early, in the presence of a gas-rich disk. Such planets interact gravitationally with the disk gas, inducing their orbital migration. Disk migration theory predicts, however, that planets would end up at resonant orbits due to their differential migration speed.  

    Motivated by the discrepancy between observation and theory, we seek for a mechanism that moves planets out of resonances. We examine the orbital evolution of planet pairs near the magnetospheric cavity during the gas disk dispersal phase. As planets migrate outward with the expanding magnetospheric cavity, their dynamical configurations can be rearranged. Our study determines the conditions under which planets can escape resonances. The proposed Magnetospheric rebound   mechanism is  promising to reconcile disk migration theory with observations. Even when planets are trapped into MMR during the early gas-rich stage, subsequent cavity expansion would induce substantial changes to their orbits, moving them out of resonance.