Evolution in the Hertzsprung-Russell (HR) diagram for a ﹩2.5\;{{\rm{M}}}_{\odot }﹩ star transferring mass to a ﹩1.4\;{{\rm{M}}}_{\odot }﹩ point mass, assuming a mass transfer efficiency of ﹩1\%﹩. Symbols are shown at zero-age main sequence (ZAMS) and terminal-age main sequence (TAMS), together with parts of the track where RLOF is occurring. The inset shows evolution from ZAMS up to the beginning of the first phase of mass transfer.