Issue A&A Volume 445, Number 3, January III 2006 Page(s) 875 - 888 Section Extragalactic astronomy DOI 10.1051/0004-6361:20053442

A&A 445, 875-888 (2006)
DOI: 10.1051/0004-6361:20053442

Dynamical and chemical evolution of NGC 1569

S. Recchi¹, G. Hensler¹, L. Angeretti² and F. Matteucci<sup>3

1</sup>  Institute of Astronomy, Vienna University, Türkenschanzstrasse 17, 1180 Vienna, Austria
    e-mail: recchi@astro.univie.ac.at
²  INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
³  Dipartimento di Astronomia, Università di Trieste, via GB Tiepolo, 11, 34131 Trieste, Italy

(Received 16 May 2005 / Accepted 7 September 2005 )

Abstract
Blue Compact Dwarf and Dwarf Irregular galaxies are generally believed to be unevolved objects, due to their blue colors, compact appearance and large gas fractions. Many of these objects show an ongoing intense burst of star formation or have experienced it in the recent past. By means of 2-D hydrodynamical simulations, coupled with detailed chemical yields originating from SNeII, SNeIa, and intermediate-mass stars, we study the dynamical and chemical evolution of model galaxies with structural parameters similar to NGC 1569, a prototypical starburst galaxy. A burst of star formation with short duration is not able to account for the chemical and morphological properties of this galaxy. The best way to reproduce the chemical composition of this object is by assuming long-lasting episodes of star formation and a more recent burst, separated from the previous episodes by a short quiescent period. The last burst of star formation, in most of the explored cases, does not affect the chemical composition of the galaxy, since the enriched gas produced by young stars is in a too hot phase to be detectable with the optical spectroscopy. Models assuming the infall of a big cloud towards the center of the galaxy reproduce the chemical composition of the NGC 1569, but the pressure exercised by the cloud hampers the expansion of the galactic wind, at variance with what observed in NGC 1569.

Key words: hydrodynamics -- ISM: abundances -- ISM: jets and outflows -- galaxies: evolution -- galaxies: individual: NGC 1569

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