Near-pristine gas at high redshifts: A window on early nucleosynthesis

Abstract

It has now become recognised that damped Lyman alpha systems-gas clouds of neutral hydrogen observed in the high redshift Universe-play an important role in helping us unravel the origin of chemical elements. Here we describe the main results of a recently completed survey of the most metal-poor DLAs, aimed at complementing and extending studies of the oldest stars in the Galaxy. The survey has clarified a number of lingering issues concerning the abundances of C, N, O in the low metallicity regime, has revealed the existence of DLA analogues to Carbon-enhanced metal-poor stars, and is providing some of the most precise measures of the primordial abundance of Deuterium. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.