Top: classic Hertzsprung-Russell diagram for the single (circle) and binary (triangle) supergiants. Also shown are the single-star LMC evolutionary tracks of Brott et al. (2011) for v_o≃ 225 km s^-1, with the initial mass (in units of the solar mass) given on the right hand side. Bottom: analogous plot showing effective temperatures versus logarithmic surface gravity. The same evolutionary tracks are plotted, this time with the initial masses given at the bottom of each track. The green stars in both represent the five stars referred to in Sect. 2.1 as radial velocity variables.