Stellar Properties of Asymptotic Giant Branch Stars in the Dwarf Irregular Galaxy IC 1613

Broadband near-infrared images obtained with the WIRCam array of the Canada-France-Hawaii Telescope are used to investigate the properties of resolved asymptotic giant branch (AGB) stars in the dwarf irregular galaxy IC 1613. Combining our JHK(s) data with optical photometric data, AGB stars were selected in color magnitude diagrams covering a wide range of wavelength. We examined the distribution of AGB stars in the (J-K-s, H-K-s) color-color diagram, and distinguished 140 carbon-rich and 306 oxygen-rich M giant AGB stars. The number ratio of C stars to M giants (C/M) was estimated, and the metallicity of IC 1613 was derived using the C/M ratio. We also examined the local C/M ratio as a function of radial distance from the center of the galaxy, and found a small negative gradient.