HR diagram of the RSG samples in the LMC (blue circles), SMC (orange crosses), MW (black squares), and the NGC 6822 (green triangles). Four POSYDON evolutionary tracks for [Z]= − 0.7 and [Z] = 0 are shown in red and dotted dark red lines, respectively, and the points indicate intervals of 10 000 yr. The upper and right panels show the density histograms (areas equal to 1) of the effective temperature and luminosity, respectively.