Evolution of the N abundance (in number) as a function of mass-loss rate for a 30 M_⊙ star of solar metallicity and an initial rotational rate of 0.35. The evolutionary track comes from Ekström et al. (2012). The green line corresponds to the nitrogen abundance determined for the nebula from the Herschel/PACS data and the bold green line specifies where log Ṁ is between − 5.0 and − 4.6. The red line represents the location of the star according to the stellar N content and the stellar parameters from the CMFGEN model.