Recent work has raised the possibility that collisions between giant galaxies eject matter into the intergalactic medium from which dwarf galaxies may be formed (Mirabel 1992; Mirabel et al.1992, 1993; Duc & Mirabel 1994). In this scenario, star forming regions generated on the tips of tidal tails that emanate from merging disk galaxies may become gravitationally bound systems that detach from the merging system and resemble HII galaxies.
However, our study of the environment of a sample of HII galaxies has shown that the majority of HII galaxies are not formed as debris of interactions of giant galaxy pairs as suggested by Mirabel and collaborators. I propose to produce large field imaging of a sample of ultraluminous interacting IRAS galaxies to obtain the following information which may give direct impact on various areas of modern astrophysics:
1) To study the morphology of the emission line regions in order to check the hypothesis the star formation is responsible for the dust emission in the infra-red or if it is due to a super massive black hole; as well as to study the structural properties of the luminous interacting systems through surface photometry and compare with their lower luminosity counterparts.
2) The incidence of dwarf galaxy size sub-structure in tails or tips of tails of interacting systems and the study of the morphology and structural properties of these systems as compared to other star forming dwarf galaxies such as HII galaxies.