Distribution of RSG luminosities depending on the metallicity of host galaxies ([Fe/H]). The sample of the most luminous RSGs in the SMC and the LMC is from Davies et al. (2018), and three well studied RSGs in IC 1613 are from Tautvaišienė et al. (2007). The vertical lines correspond to possible luminosities for RSGs with initial masses 8−40 M_⊙ for each available metallicity in the PARSEC evolutionary tracks (Bressan et al. 2012). The range of possible theoretical effective temperatures for a given range of luminosities is presented in the colorbar.