Position of the program stars in a (T_eff,log (g)) diagram. Overlaid are evolution tracks for non-rotating stars (Ω / Ω_crit = 0) of metallicity Z = 0.014 and different initial masses (M ≤ 15 M_⊙: Georgy et al. 2013; otherwise: Ekström et al. 2012). Black filled circles and numbers mark the age in Myr. Red numbers correspond to those of Table 4. Error bars indicate 99%-confidence limits.