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>.