Elemental abundances of red supergiants measured with near-infrared high-resolution spectra

Red supergiants are a class of young, luminous stars with complicated spectra rich in molecular lines. However, their brightness makes them one of the excellent tracers for metallicity distribution in the Milky Way disk, and thus there is a demand for examining the systematic errors in the derived abundances of red supergiants in detail. To examine the systematics, we analyzed the near-infrared high-resolution spectra of ten nearby red supergiants observed with the WINERED spectrograph (0.97-1.32micron, R=28,000). As a result, we find that the metallicities of red supergiants determined in this work are in good agreement with well-established results of Cepheids. Therefore, our measurement method for red supergiants is as reliable as methods for Cepheids assuming that young stars (age<200Myr) in the Solar neighborhood have homogeneous elemental abundances, which are represented by those of gas.