Binary mass-ratio reversal
= Binary mass-ratio reversal
During binary mass-ratio reversal, an initially more massive <donor star> loses enough material that its companion becomes the more massive member. The stars retain their different prior nuclear evolution, resolving the <Algol paradox>. <Conservative binary mass transfer> shrinks the orbit before equal masses and widens it after reversal, because $a\propto(M_dM_a)^{-2}$ at fixed total mass and orbital <angular momentum>.