Left: de-reddened M_V,0 − (B − V)₀ CMD of the TO stars studied in 47 Tuc. Lines are Yonsei-Yale (Y²) isochrones (11, 12, and 13 Gyr), computed assuming Z = 0.004 ([M/H] = −0.68) and [α/ Fe] = +0.4. Line in the upper left corner shows the reddening vector assuming A_V/E(B − V) = 3.1. Right: HR diagram showing the TO sample stars in 47 Tuc, with the effective temperatures and gravities determined as described in Sects. 3.1 and 3.2. Solid lines are Y² isochrones.