Depletion and evolution timescales vs depletion value for a 0.55-M_⊙ model for , 5 × 10⁻⁸, and 1.5 × 10⁻⁷ M_⊙ yr⁻¹ (top, middle, and bottom panel, respectively) with M_d = 10⁻² M_⊙ and T₀ = 4000 K. Orange solid lines show the evolution of the models in the T_eff–[Zn/Ti] plane. Blue solid and dashed lines show evolution and depletion timescales, respectively. These timescales have been normalised by dividing by the total evolution time of the model (7000, 13 000, and 21 000 years for top, middle, and bottom, respectively).