Related papers: Nitrogen Abundances in High-z DLAs
The mechanism of dust formation in galaxies at high redshift is still unknown. Asymptotic giant branch (AGB) stars and explosions of supernovae (SNe) are possible dust producers, and non-stellar processes may substantially contribute to…
The aim of this paper is to provide the fundamental parameters and abundances for a large sample of local clump giants with a high accuracy. The selection of clump stars for the sample group was made applying a color - absolute magnitude…
With an aim to investigate how the surface abundances of intermediate-mass stars off the main sequence (evolving toward the red-giant stage) are affected by the evolution-induced envelope mixing, we spectroscopically determined the…
We investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late-type galaxies using around 3740 published spectra of HII regions. We use these data in order to provide homogeneous abundance…
We investigate the production of nitrogen in star forming galaxies with ultraviolet (UV) radiation detected by the Galaxy Evolution Explorer Satellite (GALEX). We use a sample of 8,745 GALEX emission line galaxies matched to the Sloan…
We report the APOGEE-2S$+$ discovery of a unique collection of nitrogen-enhanced mildly metal-poor giant stars, peaking at [Fe/H]$\sim -0.89$ with no carbon enrichment, toward the Small and Large Magellanic Clouds (MCs), with abundances of…
X-ray observations have shown that the chemical abundance in the starburst galaxy M82 is quite rich in Si and S compared with oxygen. Such an abundance pattern cannot be explained with any combination of conventional Type I and II supernova…
The study of carbon and oxygen abundances yields information on the time evolution and nucleosynthetic origins of these elements, yet remains relatively unexplored. At low metallicities (12+log(O/H) < 8.0), nebular carbon measurements are…
We investigate whether the observed high number of carbon- and nitrogen-enhanced extremely metal-poor stars could be explained by peculiar evolutionary properties during the core He flash at the tip of the red giant branch. For this purpose…
Using results of nucleosynthesis calculations for theoretical core-collapse supernova models with various progenitor's masses, it is shown that abundance patterns of C, Mg, Si, Ca, and H seen in extremely metal-deficient stars with [Fe/H] <…
The main objective of the present work is to ckeck if the star formation efficiency plays a relevant role in the evolution of the relative abundance N/O. We analyze the evolution of the nitrogen-to-oxygen ratio as predicted by a set of…
The latest edition of the APOGEE-2/DR14 survey catalogue and the first \texttt{Payne} data release of APOGEE abundance determinations by Ting et al. are examined. We identify 31 previously unremarked metal-poor giant stars with anomalously…
Compositions of lithium-enriched and normal giants among the GALAH survey are compared. Except for Li, the only detectable abundance difference between lithium-enriched and normal giants among the investigated elements from carbon to…
(Abbreviated) From six spectra of high-z QSOs, we select eleven metal-rich, Z>=Z_solar, and optically-thin to the ionizing radiation, N(HI)<10^17 cm^-2, absorption systems ranging between z=1.5 and z=2.9 and revealing lines of different…
GN-z11 is an unusually luminous high redshift galaxy which was recently observed to have strong nitrogen lines while at the same time lacking traditional signatures of AGN activity. These observations have been interpreted as a super-solar…
We calculate the evolution of heavy element abundances from C to Zn in the solar neighborhood adopting our new nucleosynthesis yields. Our yields are calculated for wide ranges of metallicity (Z=0-Z_\odot) and the explosion energy (normal…
During the evolution on the AGB, S-type stars are the first objects to experience s-process nucleosynthesis and third dredge-ups, and therefore to exhibit sprocess signatures in their atmospheres. Their significant mass loss rates (10^-7 to…
The evolution of the metallicity of damped Lyman alpha systems (DLAs) is investigated in order to understand the nature of these systems. The observational data on chemical abundances of DLAs are analysed with robust statistical methods,…
Oxygen and carbon-rich AGB stars - and objects directly polluted by them - are excellent laboratories to investigate the nucleosynthesis and mixing processes occurring during the later phases of the of low- and intermediate-mass star…
Our understanding of the nature of DLA systems at large redshifts, ostensibly progenitors of normal disk galaxies, depends critically on their direct identifications with galaxies, and the resulting measurements of their properties. A few…