Aspect ratios of the first core e_fc, the second core, e_sc, and the fiducial core, e_ρ, (top to bottom) of all protoplanets that form in the simulations. The colour of each symbol corresponds to different adiabatic indices, the shape to different density threshold for the gas becoming optically thick (i.e. to different disc opacities and metallicity), and the type of each symbol (filled or unfilled) to different stellar radiation fields (as marked on the graph legend).