The Metallicity of the Red Giant Branch in the Disk of NGC 6822

Deep J, H, and K' images obtained with the Canada-France-Hawaii Telescopeadaptive optics system are used to investigate the metallicity of red giantbranch (RGB) stars in three fields in the disk of the Local Group dwarfirregular galaxy NGC 6822. The slope of the RGB on the (K, J-K) color-magnitudediagrams indicates that <[Fe/H]> = -1.0 +/- 0.3. The locus of the RGB is bluerthan that of globular clusters with the same RGB slope, by an amount that isconsistent with the majority of RGB stars in these fields having an age near 3Gyr. It is demonstrated that if RGB stars in NGC 6822 are this young then themetallicity computed from the RGB slope may be ~ 0.05 dex too low.Comment: 19 pages of text; 10 figures; to appear in the PAS