Title: The Spatial and Age Distribution of Stellar Populations in DDO 190
Abstract: The spatial distribution of stellar populations, the star formation history, and other properties of the dwarf irregular (dIrr) galaxy DDO 190 have been analyzed using color-magnitude diagrams of about 3900 resolved stars and the Hα fluxes of H II regions. From the mean color index of the red giant branch (RGB), a mean metallicity [Fe/H] = -2.0 is obtained. The I magnitude of the tip of the RGB has been used to estimate the distance. DDO 190 is 2.9 ± 0.2 Mpc from the Milky Way, 2.1 Mpc from the M94 group (Cn 5-1), 2.4 Mpc from the M81 group, and 2.9 Mpc from the barycenter of the Local Group, all indicating that it is an isolated field galaxy.