Multiple starbursts in Blue Compact galaxies

Autor(en)

Simone Recchi, Francesca Matteucci, Annibale D'Ercole, Monica Tosi

Abstrakt

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, a-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 ~300 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.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Università degli Studi di Trieste, INAF-Osservatorio Astronomico di Bologna

Journal

Astronomy & Astrophysics

Band

384

Seiten

799-811

Anzahl der Seiten

13

ISSN

0004-6361

Publikationsdatum

2002

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/multiple-starbursts-in-blue-compact-galaxies(8c573269-3838-4c84-b5b6-af70ae482ab9).html