Chemical and dynamical evolution in gas-rich dwarf galaxies

Abstract

We study the effect of a single, instantaneous starburst in a gas-rich dwarf galaxy on the dynamical and chemical evolution of its interstellar medium. We consider the energetic input and the chemical yields originating from SNeII, SNeIa and intermediate-mass stars. We find that a galaxy resembling IZw18 develops a galactic wind carrying out mostly the metal-rich gas. The various metals are lost differentially and the metals produced by the SNeIa are lost more efficiently than the others. As a consequence, we find larger [$α$/Fe] ratios for the gas inside the galaxy than for the gas leaving the galaxy. Finally we find that a single burst occurring in primordial gas (without pre-enrichment), gives chemical abundances and dynamical structures in good agreement with what observed in IZw18 after $\sim$ 29 Myr from the beginning of star formation.