The spatial distribution of stellar populations , the star formation history , and other properties of the dIrr galaxy DDO 190 have been analyzed using color–magnitude diagrams ( CMDs ) of about 3900 resolved stars and the H _ { \alpha } fluxes of H ii regions .
From the mean color index of the red giant branch , a mean metallicity [ Fe/H ] = -2.0 is obtained .
The I magnitude of the TRGB has been used to estimate the distance .
DDO 190 is 2.9 \pm 0.2 Mpc from the Milky Way , 2.1 Mpc from the M 94 group ( CnV-I ) , 2.4 Mpc from the M 81 group and 2.9 Mpc from the barycenter of the Local Group , all indicating that it is an isolated , field galaxy .

The surface-brightness distribution of the galaxy is well fitted by ellipses of ellipticity e = 1 - a / b = 0.1 and P.A . = 82 ^ { \circ } .
The radial star density distribution follows an exponential law of scale length \alpha = 43 \farcs 4 , corresponding to 611 pc .
The Holmberg semi-major axis to \mu _ { B } = 26.5 is estimated to be r ^ { B } _ { 26.5 } = 3 \farcm 0 .

Stellar populations of different ages in DDO 190 show strong spatial decoupling , the oldest population appearing much more extended than the youngest .
Stars younger than 0.1 Gyr occupy only the central 40 ^ { \prime \prime } ( 0.55 kpc ) ; stars younger than a few ( \sim 4 ) Gyr extend out to \sim 80 ^ { \prime \prime } ( 125 kpc ) , and for larger galactocentric distances only older stars seem to be present .
This behavior is found in all the dIrr galaxies for which spatially extended studies have been performed and could be related with the kinematical history of the galaxy .