Critical core mass as a function of the equivalent metallicity for the simplified composition case. Purple solid line: case where water condenses and the mole fraction of water is the same as the one at the top of the atmosphere of the nominal composition case (purple line in Fig. 17). Green solid line: water condenses, but the mole fraction of water corresponds to that at T = 1000 K of the nominal composition (green line in Fig. 17). Orange dashed line: same as green curve, but in this case water is not allowed to condense.