AbstractRecent observations have revealed several Jupiter-mass planets with highly eccentric and / or misaligned orbits, which clearly suggests that dynamical processes operated in these systems. These dynamical processes may result in close encounters between Jupiter-like planets and their host stars. Using three-dimensional hydrodynamical simulations, we find that planets with cores are more likely to be retained by their host stars in contrast with previous studies which suggested that coreless planets are often ejected. We propose that after a long term evolution some gas giant planets could be transformed into super-Earths or Neptune-like planets, which is supported by our adiabatic evolution models. Finally, we analyze the orbits and structure of known planets and Kepler candidates and find that our model is capable of producing some of the shortest-period objects.