Argon, silicon and iron abundances in the damped Ly-α system I Zw 18
Department of Theoretical Astrophysics, Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia e-mail: email@example.com e-mail: firstname.lastname@example.org
2 Insitut für Theoretische Physik der Universität Frankfurt am Main, 60054 Frankfurt/Main 11, Germany e-mail: email@example.com
Corresponding author: S. A. Levshakov, firstname.lastname@example.org
Accepted: 1 May 2001
We show how the ratio of the abundances of Ar, Si and Fe as derived from FUSE absorption spectra of I Zw 18 are affected by large-scale stochastic velocity fields (mesoturbulence). 21-cm observations with high spatial resolution show the presence of velocity fields with large correlation lengths. FUSE observations were performed with a large entrance aperture which fully covered the galaxy. This means that the observed profiles are averaged over the full body of I Zw 18. Taking this into account, we show that the observations are consistent with the abundance ratios [ α-chain/Fe] being similar to those derived from Galactic metal-poor stars. Using a mesoturbulent approach, we found that the observed profiles can be reproduced well with [Fe/H] , and [Si, Ar/Fe] .
Key words: line: formation / line: profiles / galaxies: individual: I Zw 18
© ESO, 2001