Evolution of a pair of 1.28 M_⊙ + 1.02 M_⊙ on an orbit with an initial period of one day. The filled points are labeled with their corresponding ages. The open circles denote the occurrence of the RLOF at an age of ≈4.9 Gyr. At this moment, it has already exhausted its hydrogen core. Left panel: evolution of the components of the pair in the theoretical plane of bolometric luminosity vs. effective temperature. Right panel: each track in the CMD and also the track to be observed by a remote observer that cannot resolve the pair.