Effective temperature as a function of time for the models included in Figure 2. As in Figure 2, green, red, and blue solid lines correspond to models with masses of 0.35048, 0.37367, and 0.41344 M_⊙, respectively. The hatched areas indicate the T_eff interval (due to error bars) as given in Liebert et al. (1994). B3, B4, and B5 intervals overlap in the lower hatched region, meanwhile the upper one corresponds to star B6. Notice that the T_eff of the models falls inside the observed intervals during a considerable amount of time, making its detection probable.