Color–magnitude diagram of Terzan 5 (same as in Figure 3), with isochrones (Girardi et al. 2002) of different ages (see labels) superimposed. The three oldest isochrones, computed for Z = 0.01 and Y = 0.26, show that the metal-poor population is consistent with an age of 12 ± 1 Gyr. The three youngest isochrones have Z = 0.03 and Y = 0.29 and show that the metal-rich component of Terzan 5 has an age of 4.5 ± 0.5 Gyr.