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Astron. Astrophys. 337, 338-348 (1998)

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The influence of stellar energetics and dark matter on the chemical evolution of dwarf irregulars

F. Bradamante 1, 2, F. Matteucci 1, 2 and A. D'Ercole 3

1 Dipartimento di Astronomia, Università di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste, Italy
2 SISSA/ISAS, Via Beirut 2-4, I-34014 Trieste, Italy
3 Osservatorio Astronomico di Bologna, Via Zamboni 33, I-44100 Bologna, Italy

Received 16 January 1998 / Accepted 14 May 1998

Abstract

A chemical evolution model following the evolution of the abundances of H, He, C, N, O and Fe for dwarf irregular and blue compact galaxies is presented. This model takes into account detailed nucleosynthesis and computes in detail the rates of supernovae of type II and I. The star formation is assumed to have proceeded in short but intense bursts. The novelty relative to previous models is that the development of a galactic wind is studied in detail by taking into account the energy injected into the interstellar medium (ISM) from both supernovae and stellar winds from massive stars as well as the presence of dark matter halos. Both metal enriched and normal winds have been considered.
Our main conclusions are: i) a substantial amount of dark matter is required in order to avoid the complete destruction of such galaxies during strong starbursts, and ii) the energy injected by stellar winds and type Ia supernovae into the ISM is negligible relative to the total thermal energy, and in particular to the type II supernovae, which in fact, dominate the energetics during starbursts.

Key words: galaxies: abundances – galaxies: dwarf – galaxies: evolution – galaxies: irregular – cosmology: dark matter

Send offprint requests to: F. Matteucci

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© European Southern Observatory (ESO) 1998

Online publication: August 17, 1998
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