Comparison of the results from our best model with the observations of the system. The initial binary parameters are: primary mass M_p,i = 5.13 M_⊙, secondary mass M_s,i = 4.21 M_⊙, and orbital period P_orb,i = 2.24 days. Panel (a): evolution of the two components of the binary system in the Hertzsprung–Russell diagram. Panel (b): evolution of stellar masses as a function of time. Panel (c): evolution of mass-transfer rate. Panel (d): evolution of orbital period. Panel (e): evolution of the two stars in the Kiel diagram. Panel (f): evolution of the stellar radii. In these plots, the dots on the curves indicate our best binary model with parameters close to the observation. The dots with error bars represent the observed values. The hatched region indicates the observed ranges of the parameters. The blue solid and yellow dashed lines are for the primary and secondary stars, respectively.