NEUTRAL GAS DISTRIBUTIONS AND KINEMATICS OF 5 BLUE COMPACT DWARF GALAXIES

We present the results of high spatial resolution H I observations of five intrinsically compact dwarf galaxies that are currently experienc ing a strong burst of star formation. The H I maps indicate that these systems have a complex and clumpy interstellar medium. Unlike typical dwarf irregular galaxies, these blue compact dwarf galaxies (BCDs) ex hibit strong central concentrations in their neutral gas distributions that may provide a clue to the origin of their strong starburst activ ity. Furthermore, while all of the systems appear to be rotating, base d on observed velocity gradients, the kinematics are complex. All syst ems have nonordered kinematic structure at some level; some of the ext ended gas is not necessarily kinematically connected to the main syste m. The observed gas distributions and kinematics place constraints on evolutionary scenarios for BCDs. Evolutionary links between BCDs, dwar f irregular galaxies, and dwarf elliptical galaxies have been postulat ed to explain their high star formation rates and low-luminosity, low- metallicity nature. The BCDs appear to have higher central mass concen trations in both gas and stellar content than the dwarf irregulars, in dicating that evolutionary scenarios connecting these two classes will require mass redistribution. In addition, the fact that BCDs are rota tionally supported systems indicates that they are unlikely to evolve into dwarf ellipticals without substantial loss of angular momentum. T hus, while such evolutionary scenarios may still be possible with the aid of mergers or tidal interactions, the isolated nature of BCDs sugg ests that the majority of BCDs will not fade to become objects similar to the present-day dwarf ellipticals.