Theoretical variation in the mass transfer and Ṁ_d curve of the donor star. Left: theoretical variation in mass transfer until helium depletion is reached for initial masses M_i, d = 3.50 M_⊙ and M_i, g = 1.50 M_⊙, for an initial orbital period $P_{\mathrm{i},\mathrm{o}}=15\stackrel{\text{d}}{.}0$. Right: Ṁ_d curve for the best evolutionary model of the donor star measured in years. The vertical dashed gray line indicates the size increase beyond the RL due to depletion of ¹H, the solid red line the initiation of mass transfer, the green line the mass inversion, the blue line the minimum RL value of the donor, and the dashed orange line the end of optically thick mass transfer from the donor to the gainer.