Spatial distribution of ionized gas in bright barred spiral galaxies: H alpha images

CCD images of a set of 52 bright barred spiral galaxies in the narrow band filter H alpha and in the broadband I filter are presented. The sample was selected from the Shapley Ames Catalog, with IRAS fluxes characteristic of star formation and a dust temperature above T-d greater than or equal to 25 K. The study is aimed at identifying the global distribution and the underlying symmetries of the structures of ionized gas in barred galaxies. Thirty-two galaxies present H alpha emission from the innermost central regions, but the emission from nuclear rings is observed only in ten galaxies. About half of the observed galaxies show H alpha emission from several regions in the disk, and 18 galaxies display emission from along the bar. The H alpha emission from inner and outer rings are easily identified in some galaxies. Some other galaxies present a more complicated spatial distributions, probably due to tidal or direct encounters with neighboring galaxies.