HR diagram showing the position of R 40 and R 110 in different epochs, based on our estimations. The Humphreys–Davidson limit is shown as a gray line. In addition, evolutionary tracks with rotation of v_rot,ZAMS = 0.4 v_crit (dashed lines) and without rotation (dotted lines) for SMC metallicity (Georgy et al. 2013, top panel) and for solar metallicity (Ekström et al. 2012, bottom panel) are also shown. Bottom panel: we indicate the regions where LBV phase may occur according to Groh et al. (2013a).