Figure 3.

The predicted lithium abundance for various ages is plotted against temperature for a mass-loss rate of 10⁻¹¹ M_⊙/yr centered at 6,500 K. Between 10 and 12 Gyr, the subgiants originate from lithium-depleted stars. Subgiants on the 10-Gyr isochrone originate in the warm wing of the lithium dip and do not show as much depletion of stars at the bottom of the dip. Subgiants of the 12- and 13-Gyr isochrones show progressively less lithium depletion as they arise from the red wing. Observed lithium abundances (7, 8, 43) are included for comparison.