Time-dependent growth tracks (top left) and orbital tracks (top right) for the disc model with r_c, ξ, T_{eff 2} indicated at the top of the panels (DWD₁ system). The bottom left panel shows the same tracks as the top left and top right panels, but with the mass on the y-axis and the orbital radius on the x-axis. The bottom right panel shows the accretion rate of the disc described by the adopted parameters (Σ₀ = 37.53 g cm⁻²). In the top right panel, the dot-dashed line corresponds to the orbital radius where T = 1200 K. The apparently vertical lines corresponds to the gas contraction phase (see Sect. 3.1.3). The fractions of track before and after the ‘vertical’ section correspond to the pebble accretion and the runaway gas accretion phase, respectively.