arXiv:astro-ph/0002371v1 18 Feb 2000 Cosmic Evolution and Galaxy Formation: Structure, Interactions, and Feedback ASP Conference Series, Vol. 3 × 10 8 , 2000 J. Franco, E. Terlevich, O. L´opez-Cruz, and I. Aretxaga, eds. Chemical and dynamical evolution in gas-rich dwarf galaxies Simone Recchi, Francesca Matteucci Dipartimento di Astronomia, Universit`a di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy Annibale D’Ercole Osservatorio Astronomico di Bologna, Via Ranzani 1, 44127 Bologna, Italy 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 ∼ 29 Myr from the beginning of star for- mation. 1. Introduction Blue compact dwarf galaxies (BCD) are gas-rich systems experiencing an in- tense star formation. These galaxies have very simple structures, small sizes and are very metal poor. For these reasons, BCD are excellent laboratories to investigate the effect of a starburst on the chemical and dynamical evolution of the interstellar medium (ISM). Previous dynamical and chemical studies of these galaxies have suggested the existence of a ‘differential galactic wind’, in the sense that after a starburst event these objects would loose mostly metals (ref. Mac Low & Ferrara 1999; D’Ercole & Brighenti 1999; Pilyugin 1992, 1993; Marconi et al. 1994). However, in none of these studies, detailed chemical and dynamical evolution was taken into account at the same time. The aim of this paper is to include the effects (both energetic and chemical) of type II and type Ia SNe in a detailed dynamical model. 1