The temperatures of red supergiants in low-metallicity environments

The temperatures of red supergiants (RSGs) are expected to depend on metallicity (Z) in such a way that lower-Z RSGs warmer. In this work, we investigate the Z-dependence Hayashi limit by analysing low-Z galaxy Wolf-Lundmark-Mellote (WLM), and compare with higher-Z environments Small Magellanic Cloud (SMC) Large (LMC). We determine effective temperature ($T_{\textrm{eff}}$) each star fitting their spectral energy distributions, as observed VLT+SHOOTER, MARCS model atmospheres. find average $T_{\textrm{eff}_{\textrm{WLM}}}=4400\pm202$ K, $T_{\textrm{eff}_{\textrm{SMC}}}=4130\pm103$ $T_{\textrm{eff}_{\textrm{LMC}}}=4140\pm148$ K. From population synthesis analysis, although Geneva evolutionary models reproduce trend qualitatively, these systematically too cool. speculate our results can be explained inapplicability standard solar mixing length RSGs.