Unusual metal abundances in a pair of damped Lyman alpha systems at z similar to 2

Citation
Sl. Ellison et S. Lopez, Unusual metal abundances in a pair of damped Lyman alpha systems at z similar to 2, ASTRON ASTR, 380(1), 2001, pp. 117-122
Citations number
27
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY & ASTROPHYSICS
ISSN journal
14320746 → ACNP
Volume
380
Issue
1
Year of publication
2001
Pages
117 - 122
Database
ISI
SICI code
1432-0746(200112)380:1<117:UMAIAP>2.0.ZU;2-6
Abstract
We present high resolution spectroscopic observations of two neighbouring d amped Lyman alpha systems (DLAs) along the same line of sight towards B2314 -409. Due to their separation (v similar to 2000 km s(-1)) and the high spe ctral resolution of the data, it is possible to fit not only the weak metal transitions, but also the separate H I absorption profiles. This has permi tted, for the first time, a detailed study of metal abundances in two neigh bouring galaxy-scale absorbers. The two DLAs have z(abs) = 1.8573 and 1.874 5 and have column densities log N(H I) = 20.9 +/-0.1 and 20.1 +/-0.2 respec tively. We have determined abundances for a range of chemical elements, and find that both absorbers towards B2314-409 have low alpha /Fe-peak abundan ces compared with other known DLAs. This indicates that not only has the re cent star formation history of these absorbers been relatively passive, but that the group environment, or some other external factor, may have influe nced this.