THE EFFECT OF CENTRAL STARBURSTS ON THE INTERSTELLAR-MEDIUM OF DWARF GALAXIES

Major starburst events can last tens of millions of years, and in the process they can deposit significant amounts of energy into the surrou nding interstellar medium. This energy from supernova and stellar wind s imparts enough momentum to the interstellar medium (ISM) that portio ns of the ISM can become unbound and leave the parent galaxy, taking t he, metal-enriched stellar debris along. In dwarf galaxies, starbursts can produce enough total energy to unbind most or all of the ambient ISM. Whether this actually occurs is a strong function of the elliptic ity of the ISM distribution, with flat disks and spheres being the lim iting cases. We calculate whether '' blow out '' along the symmetry ax is of '' blow away '' of the entire ISM occurs during a central starbu rst in dwarf galaxies as a function of galactic mass, starburst energy , ISM density, and ISM ellipticity. The calculations cover a range of 107-10(9) M. for dwarf galaxies and include ''normal'' galaxies of 10( 11) M. as well. No massive dark matter halos are assumed to be present . We find that for physically reasonable values of total ISM mass and starburst energy a blow out along the symmetry axis occurs in the majo rity of cases, though a significant fraction of small dwarf galaxies c an lose most of their ISM. As no dark matter halos or clumpy ISM distr ibutions are included, it is apparent that the ISM in most dwarf galax ies may be generally resistant to significant disruption by a central starburst event. The effects of this range of behavior on the metallic ities that would be observed in these galaxies is discussed.