Evolutionary tracks of 25 and 40 M_⊙ non-rotating (dotted lines) and rotating (solid lines) with a velocity of 300 km s^-1. The model assumes a star with near solar metallicity (Z = 0.02) evolving from the zero-age main sequence to the red supergiant and then Wolf-Rayet star phase. The dot-dashed line denotes the empirical upper luminosity boundary (for T_eff less than 6000 K) from Schuster et al. (2006). The filled circle labeled “VY CMa” represents the results for that star from Choi et al. (2008). For NML Cyg the filled circle labeled “A” corresponds to T_eff  = 2500 K (Rowan-Robinson & Harris 1983; Monnier et al. 1997; Zubko et al. 2004) and 2.7 × 10⁵L_⊙ revised with the distance in this paper; filled circles “B” and “C” are for T_eff = 2500 K and 3.0 × 10⁵L_⊙ (Schuster et al. 2009) and T_eff  = 3250 K (Ridgway et al. 1986) and 2.7 × 10⁵L_⊙.