The evolved red stellar contents of the sculptor group galaxies NGC 55, NGC 300, and NGC 7793

摘要

Deep J, H, and K images are used to probe the evolved stellar contents in the central regions of the Sculptor Group galaxies NGC 55, NGC 300, and NGC 7793. The brightest stars are massive red super- Giants(RSGs) with K ～15-15.5. The peak RSG brightness is constant to within ～0.5 mag in K, sug- gesting that NGC 55, NGC 300, and NGC 7793 are at comparable distances. Comparisons with bright RSGs in the Magellanic Clouds indicate that the difference in distance modulus with respect to the LMC is Δμ=7.5 mag.