相关论文: Light Element Abundances From z=0 To z=5
We present the analysis of an extensive set of new and literature high quality data concerning Fe, C, N, O, Na, and Mg, exploiting the Teff scale determined in Gratton et al. (1996), and the non-LTE abundance corrections computed in Gratton…
Abundances of five elements, Na, Mg, Al, Si, and Sr, are investigated for 44 very metal-poor stars (-4.0 < [Fe/H] < -1.5) in the Galactic halo system based on an Local Thermodinamic Equilibrium (LTE) analysis of high-resolution…
We present the first D/H measurement in a damped Ly-alpha system at z_abs = 3.025 towards QSO 0347-3819 obtained from the UVES-VLT spectra. The DLA absorber has a metallicity of [Zn/H] = -1.25 and a relatively simple velocity structure,…
We use our unified chemical and spectrophotometric evolutionary synthesis code to describe galaxies of various Hubble types. With stellar evolutionary tracks and element yields for 5 different metallicities we follow the spectrophotometric…
Many works have found unusual characteristics of elemental abundances in nearby dwarf galaxies. This implies that there is a key factor of galactic evolution that is different from that of the Milky Way (MW). The chemical abundances of the…
We have used UVES on VLT-UT2 to take spectra of 15 red giants in the Sculptor, Fornax, Carina and Leo I dwarf spheroidal galaxies. We measure the abundances of alpha, iron peak, s and r-process elements. No dSph giants in our sample show…
Abundance matching between galaxies and halos has proven to be an informative technique, less dependent on detailed physical approximations than some other methods. We extend the discussion to the dwarf galaxies realm and to the study of…
We present an analysis of eight star-forming galaxies with $\langle z \rangle = 4.0$ from the JWST EXCELS survey for which we obtain robust chemical abundance estimates for the $\alpha$-elements O, Ne and Ar. The $\alpha$-elements are…
The recent determination of the baryon-to-photon ratio from WMAP data by Spergel et al. (2003) allows one to fix with unprecedented precision the primordial abundances of the light elements D, 3He, 4He and 7Li in the framework of the…
In this review I outline some ideas in chemical evolution, necessary for understanding the evolution of galaxies from measured elemental abundance ratios. I then discuss abundance results from studies of Local Group dwarf galaxies and the…
We have studied a sample of 11 blue, luminous, metal-poor galaxies at redshift 0.744 < z < 0.835 from the DEEP2 redshift survey. They were selected by the presence of the [OIII]4363 auroral line and the [OII]3726,3729 doublet together with…
It is well-established that the vast majority of metal-poor Galactic halo stars shows evidence for enrichment by solely massive stars. Recent observations have identified more varied behavior in the pattern of elemental abundances measured…
By means of chemo-photometric models for galaxies of different morhological types, we have carried out a detailed study of the history of element production by spheroidal and dwarf irregular galaxies. Spheroidal galaxies suffer a strong and…
We present a search for metal absorption line systems at the highest redshifts to date using a deep (30h) VLT/X-Shooter spectrum of the z = 7.084 quasi-stellar object (QSO) ULAS J1120+0641. We detect seven intervening systems at z > 5.5,…
We present abundance measurements of the elements Zn, S, O, C, Si and Fe for four sub-DLAs at redshifts ranging from z=2.173 to z=2.635 using observations from the MIKE spectrograph on the Magellan telescope to constrain the chemical…
We present a survey of lithium abundances in 185 main- sequence field stars with Teff between 5600 and 6600 K and [Fe/H] from -1.4 to +0.2 based on high-resolution spectra of 130 stars and a reanalysis of data from Lambert et al. (1991).…
Star-to-star variations in abundances of the light elements carbon, nitrogen, oxygen, and sodium have been observed in stars of all evolutionary phases in all Galactic globular clusters that have been thoroughly studied. The data available…
Metal-poor M subdwarfs are among the oldest stellar populations and carry valuable information about the chemical enrichment history of the Milky Way. The measurements of chemical abundances of these stars therefore provide essential…
Observations show that the global deuterium-to-hydrogen ratio (D/H) in the local interstellar medium (ISM) is about 90% of the primordial ratio predicted by big bang nucleosynthesis. The high (D/H)$_{ISM}$ implies that only a small fraction…
Abundances of lithium, carbon, and oxygen have been derived using spectral synthesis for a sample of 249 bright F, G, and K Northern Hemisphere dwarf stars from the high-resolution spectra acquired with the VUES spectrograph at the Moletai…