  Detailed analysis of the spectral lines from two low redshift damped Lyman
alpha absorbers (DLA) confirms that they are a heterogeneous population. Both
systems have low metal abundances of approximately 0.05 to 0.1 solar. The
abundance pattern of the DLA at z=1.15 towards HE 0515-4414 shows dust
depletion comparable to that found in our Galaxy, while the system at z=0.68
towards HE 1122-1649 shows abundance ratios resembling metal-poor halo stars
with no dust depletion, for a comparable HI column. Constraints for N/Fe and
N/Si also hint at z=0.68 DLA as a galaxy with recent star formation. The trend
of increasing CI/HI with decreasing z is discussed. Only weak absorption from
highly-ionized species associated with the DLA at moderate z have been detected
and it probably originates in regions distinct from the low ionization gas. The
low-ion profiles show very complex structures and are too large to be explained
by the rotation of a disk: the system at z=0.68 spans over approximately 300
km/s and the z=1.15 DLA presents substructure over more than 700 km/s, the
largest velocity extent found up to date for a DLA.

Astrophysics