The structure of the irregular galaxy, NGC 3239

UBVR surface photometry of the irregular galaxy, NGC 3239, has been combined with H-alpha and neutral hydrogen data to show it to be a galaxy with new star formation, a possible remnant of disk structure, tails, separate kinematical systems of gas and luminous matter, many H II regions including a giant H II region, and colors appropriate to a late Hubble type. Its colors indicate the presence of regions of vigorous star formation in some areas (including one of the tails) and the predominance of old stars in other areas (including the other tail). The model of merging galaxies fits NGC 3239 very well because it has (1) tails presumed to be tidal but no nearby companions, (2) a disturbed structure including a warped disk, (3) a structure that is multiple kinematically with an enhanced velocity dispersion, (4) a portion of a disk that is free of H I while other portions of the disk contain H I, and (5) H II regions and stellar associations indicating recent star formation.