HR diagrams summarizing our simulations described in Sect. 4.2. Black and blue dots show the location of the primary component of ExtEV, according to this paper and the study of J21, respectively. The gray curves show evolutionary tracks that never approach the position of the primary component determined in our study. Conversely, multicolored tracks correspond to those that are within the error box of the ExtEV (black dot) at some phase of the evolution. The color bar above the HR diagrams reflects M_1, ZAMS (left panel) and M₁ (right panel) and is common to both panels.