We compare star formation in the inner and outer disks of 11 dwarf Irregular galaxies ( dIm ) within 3.6 Mpc .
The regions are identified on GALEX near-UV images , and modeled with UV , optical , and near-IR colors to determine masses and ages .
A few galaxies have made 10 ^ { 5 } -10 ^ { 6 } M _ { \odot } complexes in a starburst phase , while others have not formed clusters in the last 50 Myrs .
The maximum region mass correlates with the number of regions as expected from the size-of-sample effect .
We find no radial gradients in region masses and ages , even beyond the realm of H \alpha emission , although there is an exponential decrease in the luminosity density and number density of the regions with radius .
H \alpha is apparently lacking in the outer parts only because nebular emission around massive stars is too faint to see .
The outermost regions for the 5 galaxies with HI data formed at average gas surface densities of 1.9-5.9 M _ { \sun } pc ^ { -2 } .
These densities are at the low end of commonly-considered thresholds for star formation and imply either that local gas densities are higher before star formation begins or sub-threshold star formation is possible .
The first case could be explained by supernovae triggering and other local processes , while the second case could be explained by gravitational instabilities with angular momentum loss in growing condensations .
The distribution of regions on a \log ( { Mass } ) - \log ( { age } ) plot is examined .
The distribution is usually uniform along \log ( { age } ) for equal intervals of \log ( { Mass } ) and this implies a region count that varies as 1 / { age } .
This variation results from either an individual region mass that varies as 1 / { age } or a region disruption probability that varies as 1 / { age } .
A correlation between fading-corrected surface brightness and age suggests the former .
The implied loss of mass is from fading of region envelopes below the surface brightness limit .