As Metal Poor as It Could Be: the Damped System at z=3.390 Towards QSO 0000-2619

Abstract

We present an abundance analysis of the damped Lya system seen in the spectrum of the QSO 0000-2619 at z _abs=3.390. From the analysis of high resolution spectra (FWHM ⋍ 11 and 14 km s⁻¹) we identify lines of N I, O I, Al II, Si II and Fe II. The gas phase abundances are [Fe/H]=−2.3, [Si/H]=−2.7, [N/H]=−2.7, [O/H]=−3.1, and [Al/H]=−2.8 relative to the solar value, i.e. at the lowest level found so far in DLAs. The relative abundances show an enhancement of Fe compared to α elements, which is the opposite of what observed in halo stars. Such a behaviour is expected in chemical evolution models when a burst of star formation is followed by a quiescent phase.