Abundances in the ISM of Star-Forming Galaxies from FUSE Observations: the case of I Zw 18
Publication date: 02 March 2006
Authors: Aloisi, A., et al.
Journal: Space Telescope Science Institute Symposium Series
Volume: 17
Issue: The Local Group as an Astrophysical Laboratory
Year: 2006
Copyright: CUP
We report on the analysis of the FUSE spectrum of the most metal-poor blue compact dwarf (BCD) galaxy I Zw 18. From a simultaneous fitting of HI and metal absorption lines arising from the neutral interstellar medium (ISM), we infer abundances of heavy elements (Fe, O, Si, Ar, and N) which are several times lower than in the HII regions. The only exception is Fe, whose abundance is the same. The abundance pattern of the ISM suggests ancient star formation (SF) activity with an age of at least a Gyr that enriched the H i phase. A more recent episode that started 10 to several 100 Myr ago is responsible for the additional enrichment of alpha-elements and N in the HII regions.
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