相关论文: Chemical evolution and depletion pattern in Damped…

We report the identification of a very metal-poor damped Lyman-alpha system (DLA) at z_abs = 3.067295 that is modestly carbon-enhanced, with an iron abundance of ~1/700 solar ([Fe/H] = -2.84) and [C,O/Fe] ~ +0.6. Such an abundance pattern…

We characterize the importance of metallicity on the presence of molecular hydrogen in damped Lyman-alpha (DLA) systems. We construct a representative sample of 18 DLA/sub-DLA systems with log N(HI)>19.5 at high redshift (zabs>1.8) with…

We use the average E(B-V) and ZnII column densities of a sample of z~1 CaII (3935, 3970) absorption line systems selected from the Sloan Digital Sky Survey (SDSS DR4) to show that on average, with conservative assumptions regarding…

We review general characteristics of massive stars, present the main observable constraints that stellar models should reproduce. We discuss the impact of massive star nucleosynthesis on the early phases of the chemical evolution of the…

We present a spectroscopic study of six damped Lya absorption (DLA) systems at z<0.65, based on moderate-to-high resolution spectra of the galaxies responsible for the absorbers. Combining known metallicity measurements of the absorbers…

In this first paper of a series, we report on the use of quasar spectra obtained with the UVES high resolution spectrograph and available through the ESO VLT archive to build the first sample of sub-DLA systems, absorbers with HI column…

With the Blue Channel Spectrograph (BCS) on the MMT telescope, we have obtained spectra to the atmospheric cutoff of quasars previously known to show at least one absorption system at z>1.6 with very strong metal lines (candidate…

We analyze extant data of Al++, Al+ and other low ions with the aim of studying the ionization properties of Damped Ly alpha systems (DLAs) from the analysis of the ratio R(Al++/Al+) = N(Al++)/N(Al+). We find good correlations…

We investigate chemical abundance variations along the sightlines through 13 damped Lya systems (DLA). We introduce a technique designed to identify abundance variations in multiple velocity bins along the sightlines and perform a series of…

By means of detailed chemical evolution models for galaxies of different morphological types (i.e. spirals, irregular/starburst galaxies and ellipticals) we study the nature of Damped Lyman-Alpha systems. Our concern is to infer which…

We used our database of ESO VLT-UVES spectra of quasars to build up a sample of 67 Damped Lyman-alpha (DLA) systems with redshifts 1.7<zabs<3.7. For each system, we measured average metallicities relative to Solar, [X/H] (with either X=Zn,…

Recently revealed C, N, and O abundances in the most metal-poor damped Lyman-alpha (DLA) absorbers are compared with those of extremely metal-poor stars in the Galactic halo, as well as extragalactic H II regions, to decipher…

Measurements of element abundances in damped Lyman alpha systems are providing new means to investigate the chemical evolution of galaxies, particularly at early times. We review progress in this area, concentrating on recent efforts to…

We used our database of VLT-UVES quasar spectra to build up a sample of 70 Damped Lyman-alpha (DLA) or strong sub-DLA systems with total neutral hydrogen column densities of log N(HI)>20 and redshifts in the range 1.7<z_abs<4.3. For each of…

I review measurements of element abundances in different components of the high redshift universe, including the Lyman alpha forest, damped Lyman alpha systems, and Lyman break galaxies. Although progress is being made in all three areas,…

Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest and a…

We have identified a metal-strong (logN(Zn+) > 13.15 or logN(Si+) > 15.95) DLA (MSDLA) population from an automated quasar (QSO) absorber search in the Sloan Digital Sky Survey Data Release 3 (SDSS-DR3) quasar sample, and find that MSDLAs…

Motivated by the anomalous dust-to-metal ratios derived in the literature for gamma-ray burst (GRB) damped Lyman-alpha absorbers (DLAs), we measure these ratios using the dust-depletion pattern observed in UV/optical afterglow spectra…

We present a study of Ar abundances in 15 damped Ly alpha systems (DLAs) in the redshift interval from 2.3 to 3.4. The sample includes 4 new UVES/VLT measurements of Ar I column densities. The majority of DLAs show significant…

The distribution of element abundances with redshift in Damped Ly-alpha (DLA) systems can be adequately reproduced by the same model reproducing the halo and disk components of the Milky Way Galaxy at different galactocentric distances: DLA…