2000/08/23 by Ana de la Varga, A. de la Varga, D. Reimers +10
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Calibration and Measurement Techniques #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0008366
35 pages, 8 figures, accepted for publication in A&A
arxiv created 2000/08/23 · openalex publication_date 2000/08/23 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
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.