Radius-dependent physical profiles of the three mass-accretion rates used in the chemical models. Panels a to c show temperature profiles as a function of radius, whereas panels d to f show density profiles as a function of radius. Upper panels a and d correspond to the 3.0 × 10⁻³ M_⊙ yr⁻¹ mass-accretion rate, middle panels b and e correspond to the 1.0 × 10⁻³ M_⊙ yr⁻¹ mass-accretion rate, and the lower panels c and f correspond to the 1.0 × 10⁻⁴ M_⊙ yr⁻¹ mass-accretion rate. The black curves represent the final stage-2 simulation time, the green curves represent a stage-2 simulation time corresponding to 100 K for the innermost trajectory of each mass-accretion rate, and the red curves represent the initial stage-2 simulation time. It should be noted that the range for the horizontal axis is different for models of different mass-accretion rates.