Periodic solutions of a perturbed Kepler problem in the plane: from existence to stability
arXiv:1703.07857 · doi:10.1016/j.jde.2016.05.004
Abstract
The existence of elliptic periodic solutions of a perturbed Kepler problem is proved. The equations are in the plane and the perturbation depends periodically on time. The proof is based on a local description of the symplectic group in two degrees of freedom.