Issue |
A&A
Volume 384, Number 3, March IV 2002
|
|
---|---|---|
Page(s) | 799 - 811 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020083 | |
Published online | 15 March 2002 |
Multiple starbursts in Blue Compact Galaxies
1
Dipartimento di Astronomia, Università di Trieste, Via G. B. Tiepolo 11, 34131 Trieste, Italy
2
Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
Corresponding authors: S. Recchi, recchi@ts.astro.it matteucci@ts.astro.it annibale@bo.astro.it tosi@bo.astro.it
Received:
28
August
2001
Accepted:
18
December
2002
In this paper we present some results concerning the effects of two
instantaneous starbursts, separated by a quiescent period, on the
dynamical and chemical evolution of Blue Compact Dwarf galaxies. In
particular, we compare the model results to the galaxy IZw18, which is
a very metal-poor, gas-rich dwarf galaxy, possibly experiencing its
first or second burst of star formation. We follow the evolution of a
first weak burst of star formation followed by a second more intense
one occurring after several hundred million years. We find that a
galactic wind develops only during the second burst and that metals
produced in the burst are preferentially lost, relative to the hydrogen
gas. We predict the evolution of several chemical abundances (H, He,
C, N, O, α-elements, Fe) in the gas inside and outside the
galaxy, by taking into account, in detail, the chemical and energetical
contributions from type II and Ia supernovae. We find that the
abundances predicted for the star forming region are in good agreement
with the H ii region abundances derived for IZw18. We also predict the
abundances of C, N and O expected for the H i gas to be compared with
future FUSE abundance determinations. We conclude that IZw18 must
have experienced two bursts of star formation, one occurred ~ Myr ago and a recent one with an age between 4–7 Myr. However, by
taking into account also other independent estimates, such as the
color-magnitude diagram and the spectral energy distribution of stars
in IZw18, and the fact that real starbursts are not instantaneous, we
suggest that it is more likely that the burst age is between 4 and 15
Myr.
Key words: galaxies: evolution / hydrodynamics / ISM: abundances / ISM: bubbles
© ESO, 2002
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