Similar to Fig. 12, but for the case of a 25 M_⊙ donor at LMC composition and five different initial orbital periods. The legend on top details what was the evolutionary state of the donor at the onset of RLOF (HG phase or core-He burning) as well as the main outcome of the mass transfer interaction (hot stripped star, partially stripped star, or nuclear-timescale mass transfer). The mass-radius exponent in the third panel is defined as ζ_th = dlog R_th; eq/dlog M_don as derives directly from the results in the second panel. Horizontal lines show the mass-radius exponent of the donor’s Roche lobe ζ_RL = dlog R_RL/dlog M_don assuming a fully nonconservative mass transfer. The behavior of ζ_th as a function of the remaining donor mass can be linked to various features found in binary models, see text.