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Fig. 2


Left panels: nitrogen abundance as a function of the helium abundance () for this work (with cooler and hotter stars depicted in the first and second rows, respectively) and previous non-LTE studies in the literature (Gies & Lambert 1992; Morel et al. 2008; Bouret et al. 2012, 2013; Rivero González et al. 2012a,b; Martins et al. 2015b; Grin et al. 2017). The very He-rich stars of Gies & Lambert (1992) are highlighted as filled symbols. The helium data of Morel et al. (2008) are supplemented by results from Morel et al. (2006), Briquet & Morel (2007), Briquet et al. (2007), and Hubrig et al. (2008). Sample stars of Rivero González et al. (2012a) and Rivero González et al. (2012b) are shown in blue and black, respectively. Typical error bars are shown to the right of each panel. The dashed lines show the baseline abundances of Brott et al. (2011a) for the Galaxy and the Magellanic Clouds. Central panels: breakdown of vsin i values. Right panels: positions of the stars in the Kiel diagram. Evolutionary tracks from Brott et al. (2011a) for the relevant metallicity are overplotted. Initial stellar masses (in solar units) are indicated. Rotational velocities at the ZAMS of Galaxy models for stellar masses higher than 12 M are listed in Table 1; for 7, 9, and 12 M, the initial rotational velocities are chosen to be close to that of the 15 M model, i.e. 339, 333, and 331 km s-1, respectively. Assumed rotational velocities at the ZAMS of Magellanic Cloud models are close to the ones of Galaxy models for each mass. Lower and upper limits are ignored in all plots.

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