Hertzsprung-Russell diagram based of the M 31 late-WN sample, this time with instead of T_∗. For comparison, known LBVs (filled circles) and LBV candidates (open circles) are shown. The gray-shaded area marks the S Dor instability strip (Wolf 1989). The empirical Humphreys-Davidson limit is also indicated. The parameters of the comparison stars are taken from Nazé et al. (2012) with the exception of Romano‘s Star (V532, Clark et al. 2012; Maryeva & Abolmasov 2012) and the Peony star (Barniske et al. 2008). The locations of LBVs in different stages are connected by dashed lines. Labels without letters refer to the M31WR numbers as listed in Table 2.