Several cycles from our evolutionary models in Sect. 4 in the HR diagram, color-coded according to their sonic-point temperature. Each dot corresponds to a computed stellar model during our evolutionary calculation. Superposed, we show the location in the HR diagram of the minimum and maximum brightness phase of AG Carinae (gray dots and dashed line) from Vink (2012, Fig. 1). The effective temperature at optical depth unity is estimated with the wind models discussed in Sect. 2, while the bolometric luminosity has been decreased by 0.05 dex to correspond to that of AG Carinae.