Evolutionary path in the HR diagram of a 55 M_⊙ star of solar metallicity and for initial rotation rates Ω / Ω_crit from 0 to 0.4, using the models of Ekström et al. (2012). The thicker lines emphasize the part of the tracks compatible with the N/O abundance ratio and the mass-loss rate. For clarity, the tracks are stopped during the He burning phase (data point n^o 195 in Ekström et al. 2012).