The Nature of Starbursts: III. The Spatial Distribution of Star
  Formation
  We map the spatial distribution of recent star formation over a few x 100 Myr
timescales in fifteen starburst dwarf galaxies using the location of young blue
helium burning stars identified from optically resolved stellar populations in
archival Hubble Space Telescope observations. By comparing the star formation
histories from both the high surface brightness central regions and the diffuse
outer regions, we measure the degree to which the star formation has been
centrally concentrated during the galaxies' starbursts, using three different
metrics for the spatial concentration. We find that the galaxies span a full
range in spatial concentration, from highly centralized to broadly distributed
star formation. Since most starbursts have historically been identified by
relatively short timescale star formation tracers (e.g., Halpha emission),
there could be a strong bias towards classifying only those galaxies with
recent, centralized star formation as starbursts, while missing starbursts that
are spatially distributed.
