• The sub-damped Ly a system [alpha system] toward HE 0515-4414 

      Quast, Ralf (Univ. Hamburg, 2006)
      Context Extragalactic absorbers with column densities exceeding NH I > 2 × 1020 hydrogen atoms cm-2 are generally termed damped Ly alpha (DLA) systems. The absorbers are basically comprised of predominantly neutral gas, ...