Luminosity-mass relation of postinteraction donor stars in detached binaries with R/R_RL < 0.6 at the LMC metallicity. The colors correspond to the few selected donor tracks from binary models shown in the HR diagram in Fig. 9, with crosses (spaced by 50 000 yr) marking the position occupied for most of the evolution since the onset of RLOF. Gray lines show the evolution of single stars with the corresponding masses. Similarly to Fig. 9, in grayscale we plot the distribution of postinteraction stars in detached systems from all the grid models (except those interacting on MS). The figure demonstrates that mass transfer can produce partially stripped stars that may appear significantly undermassive for their apparent evolutionary mass (as one would deduce from single tracks). Note, however, that models with M₁ ≤ 14 M_⊙ produce postinteraction stars that are hot stripped stars (T_eff > T_eff; ZAMS).