Program: GN-2021A-Q-214

We propose to measure stellar metallicities of blue supergiants in the low-metallicity dwarf irregular galaxy NGC 2366 (D=3.3 Mpc). These measurements will be compared to the chemical composition derived from HII regions, using published metal recombination (RL) and collisionally excited (CEL) emission line data. A study by the co-Is, based on stellar and nebular chemical abundance data, suggests that HII region metallicities derived from RLs progressively diverge from stellar metallicities with decreasing metallicity. The classical, direct method of measuring nebular abundances, based instead on CELs, does not show this behavior. NGC 2366 offers us the unique opportunity to compare stellar and gas-phase abundances at metallicities below the SMC. The result will be important to test the reliability of gas-phase chemical abundance determination methods.