Critical core mass as a function of metallicity for the specified semi-major axis and corresponding boundary conditions given by Eqs. (21) and (22). Dashed lines correspond to the reference cases (boundary conditions at a = 5.2 AU) plotted in Fig. 1: the yellow curve is the restricted case (i.e. without condensation of water), and the blue curve the non-restricted case (where water condenses). For all the new cases (solid lines) water is allowed to condense. The only case where water does not condense for any value of Z is for a = 2 AU.