Unusual metal abundances in a pair of damped Lyman alpha systems at ^*

¹ European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: sellison@eso.org
² Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile e-mail: slopez@das.uchile.cl

Corresponding author: S. Ellison, sellison@eso.org

Received: 4 September 2001
Accepted: 9 October 2001

Abstract

We present high resolution spectroscopic observations of two neighbouring damped Lyman α systems (DLAs) along the same line of sight towards B2314-409. Due to their separation ( km s^-1) and the high spectral 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 permitted, for the first time, a detailed study of metal abundances in two neighbouring galaxy-scale absorbers. The two DLAs have z_abs = 1.8573 and 1.8745 and have column densities N(H I) = and respectively. We have determined abundances for a range of chemical elements, and find that both absorbers towards B2314-409 have low α/Fe-peak abundances compared with other known DLAs. This indicates that not only has the recent star formation history of these absorbers been relatively passive, but that the group environment, or some other external factor, may have influenced this.