Theoretical models show that Hot Jupiters and Hot Neptunes can evolve by hydrodynamic loss of their atmospheres to Mini-Neptunes (as it could be the Super-Earth GJ 1214 b),Charbonneau, David et al. (2009), A super-Earth transiting a nearby low-mass star, Nature 462, p.891–894 or even to rocky planets known as chthonian planets (after migrating towards the proximity of their parent star). The amount of the outermost layers that is lost depends on the size and the material of the planet and the distance from the star. In a typical system a gas giant orbiting 0.02 AU around its parent star loses 5–7% of its mass during its lifetime, but orbiting closer than 0.015 AU can mean evaporation of the whole planet except for its core.Sotin, Christophe; Grasset, O.; Mocquet, A. (2013), Are terrestrial exoplanets Earth-like, Venus-like, or the remnants of gas- or ice-giants?, American Astronomical Society.
