Hertzsprung-Russell diagram for the evolution of the initially 1.0 M_⊙ secondary star. The tracks corresponding to initial orbital periods of 0.90 and 1.40d are depicted. The final mass at the end of Roche lobe overflow is, respectively, 0.15540 and 0.18685 M_⊙. RL marks the locations in the diagram when the secondary star fills its Roche lobe for the first time and mass loss begins. The color scale to the right shows the stellar mass of the secondary star.