Argon, silicon and iron abundances in the damped Ly-alpha system I Zw 18
Abstract
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 [alpha -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] =-2.4+/-0.1, and [Si, Ar/Fe] = 0.7+/-0.1.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 2001
- DOI:
- 10.1051/0004-6361:20010628
- arXiv:
- arXiv:astro-ph/0011513
- Bibcode:
- 2001A&A...373..836L
- Keywords:
-
- LINE: FORMATION;
- LINE: PROFILES;
- GALAXIES: INDIVIDUAL: I ZW 18;
- Astrophysics
- E-Print:
- 4 pages, 2 eps figure, submitted to AA