Critical mass of metals (mass content of metals in the planet when M_core = M_crit) as a function of metallicity. Red line: restricted case. Blue line: non-restricted case. Boundary conditions given by Table 1. Despite the similarity with Fig. 1, in this case the y-axis represents all the metal content of the planet at criticality, and not just that of the core. Depending on the slope of M_Z,crit(Z), for the same planetesimal accretion rate, the planet could become sub- or super-critical. The steeper the slope (water condensation case), the more likely the structure is to become sub-critical, and therefore, to follow case 1 illustrated in Fig. 19.