Abstract

The formation of Uranus and Neptune is still an open question in planetary science. According to the standard model of giant planet formation, protoplanets in the mass regime of ~15 Earth masses are expected to accrete gas rapidly. Therefore, the termination of gas accretion at the exact mass of the ice giants needs to be explained. In addition, exoplanets with sizes (and masses) similar to Uranus and Neptune are found to be very abundant in the galaxy, suggesting that their formation mechanism is very efficient. The aim of our International Team is to discuss and explore the possible formation pathways of such planets (i.e., Neptune-like, mini-Neptunes). We will also concentrate on the predicted compositions and internal structure of Uranus and Neptune, their long-term evolution, and how a better understanding of these planets can be used for exoplanetary characterisation. This will be used for the interpretation of data from the upcoming exoplanetary space missions (e.g., CHEOPS, TESS).