The formation of Mini-Neptunes

The results of the Kepler mission show that planets smaller than Neptune, presumably composed of non-negligible amounts of hydrogen and helium  ("mini-Neptunes"), are frequent. The formation of this type of objects is in principle challenging for the classical core-accretion paradigm of giant planet formation, where protoplanets start to accrete considerable amounts of gas when Mcore ~10 Mearth. I will show that mini-Neptunes are a common outcome when including the effect of envelope enrichment by icy planetesimals/pebbles in the formation models, and that there is a "sweet-spot" in terms solid mass of the disk that favour their formation. Our results favour the detection of mini-Neptunes around low-mass stars.