Accretion rate, internal structure, and luminosity as a function of the mass on the birthline. The vertical grey dotted straight lines indicate the masses M₀ of the model of the grid (Sect. 2.5). Middle panel: the upper black curve is the photospheric radius, the green (resp. grey) areas are convective (resp. radiative) regions, and the black dotted curves are iso-mass (i.e. Lagrangian layers). Lower panel: the solid line is the total photospheric luminosity and the dashed one is the luminosity produced by D-burning.