Theoretical behaviour of Q′_⋆,WB (green lines in upper panels) and M_crit (red lines in lower panels) as a function of stellar age for the planet-star systems of our sample. Green- and red-shaded areas reflect the propagation of 1 σ uncertainties in the stellar parameters used as the inputs. The horizontal dashed lines mark the actual masses of the planets. Vertical grey shading codes the system ages with the 1, 2, and more σ range marked in white, light grey, and dark grey, respectively. The values of Q′_⋆,WB are marked at the left-hand ordinates and M_crit at the right ones.