The evolution of dwarf galaxies with star formation in an outward-propagating supershell

We simulate the dynamical and chemical evolution of a dwarf galaxy embedded in a dark matter halo, using a three-dimensional N-body/smoothed particle hydrodynamics (SPH) simulation code combined with stellar population synthesis. The initial condition is adopted in accord with a 10(10) M. virialized sphere in a 1 sigma cold dark matter perturbation which contains 10% baryonic mass. A supersonic spherical outflow is driven by the first starburst near the center of the galaxy and produces an expanding supershell in which stars are subsequently formed. Consecutive formation of stars in the expanding shell makes the stellar system settled, with the exponential brightness profile, the positive metallicity gradient, and the inverse color gradient in agreement with observed features of dwarf galaxies. We therefore propose that the energy feedback via stellar winds and supernovae is a decisive mechanism for formation of less compact, small systems like dwarf galaxies.