Variation of luminosity (in mass fraction) as a function of mass coordinate inside two accreting models compared at same total luminosity. Left: total (solid), nuclear (dotted) and gravitational (dashed) luminosities versus enclosed mass fraction for the 10⁻³ M_⊙ yr⁻¹ star at a mass of 2072 M_⊙ and total luminosity of 6.9 × 10⁷ L_⊙. Right: Same as on the left but for a pre-MS 1.0 M_⊙ yr⁻¹ star at a mass of 2337 M_⊙ and same total luminosity (in this case powered only by gravitational contraction). The dot-dashed lines show mass fractions for H (left) and ³He (right) in the star. The shaded blue and grey zones depict the convective and radiative regions respectively.