On the radial abundance gradients in disks of irregular galaxies
  We determine the radial abundance distributions across the disks of fourteen
irregular galaxies of the types Sm and Im (morphological T types T = 9 and T
=10) as traced by their HII regions. The oxygen and nitrogen abundances in HII
regions are estimated through the Te method or/and with the counterpart method
(C method). Moreover, we examine the correspondence between the radial
abundance gradient and the surface brightness profile. We find that irregular
galaxies with a flat inner profile (flat or outwardly increasing surface
brightness in the central region) show shallow (if any) radial abundance
gradients. On the other hand, irregular galaxies with a steep inner profile
(with or without a bulge or central star cluster) usually show rather steep
radial abundance gradients. This is in contrast to the widely held belief that
irregular galaxies do not usually show a radial abundance gradient.
