Matches in SemOpenAlex for { <https://semopenalex.org/work/W2918789831> ?p ?o ?g. }
- W2918789831 endingPage "3543" @default.
- W2918789831 startingPage "3527" @default.
- W2918789831 abstract "Abstract The most metal-poor stars are the oldest objects, they provide a unique opportunity to study the earliest epoch of the Galaxy formation and individual nucleosynthesis events. These stars should be investigated with a scrupulous care, taking into account all available photometric, spectroscopic, and astrometric informations. We determined atmospheric parameters for 17 ultra metal-poor (UMP) stars, using an extensive method based on colour-Teff calibrations, isochrones, Gaia DR2 trigonometric parallaxes, and non-local thermodynamic equilibrium (NLTE) analysis of the Ca i/Ca ii ionization equilibrium and the Balmer line wings. We updated the model atom of Ca i- ii by including recent quantum-mechanical rate coefficients for the Ca i + H i and Ca ii + H i inelastic collisions. For any line of Ca i and Ca ii in our sample stars, the changes in collisional data result in a shift of smaller than 0.05 dex in the NLTE abundance. We determined magnesium and calcium NLTE and LTE abundances of our sample stars. For 10 stars, we found close-to-solar [Ca/Mg] NLTE abundance ratios. In the remaining stars, magnesium and calcium abundances do not follow each other, such that [Ca/Mg] varies between −3.15 and + 0.36, suggesting a contribution to stellar Mg and Ca abundances from a small number of supernova explosions with different properties. The obtained atmospheric parameters will be used in the forthcoming paper to determine NLTE abundances of chemical elements observed in spectra of the UMP stars." @default.
- W2918789831 created "2019-03-11" @default.
- W2918789831 creator A5049021876 @default.
- W2918789831 creator A5053644519 @default.
- W2918789831 creator A5053954087 @default.
- W2918789831 creator A5088168136 @default.
- W2918789831 date "2019-03-05" @default.
- W2918789831 modified "2023-10-16" @default.
- W2918789831 title "Ultra metal-poor stars: improved atmospheric parameters and NLTE abundances of magnesium and calcium" @default.
- W2918789831 cites W1515149315 @default.
- W2918789831 cites W1581050742 @default.
- W2918789831 cites W1898983771 @default.
- W2918789831 cites W1964606185 @default.
- W2918789831 cites W1964942307 @default.
- W2918789831 cites W1968035378 @default.
- W2918789831 cites W1972226679 @default.
- W2918789831 cites W1979257798 @default.
- W2918789831 cites W1990577178 @default.
- W2918789831 cites W1992466169 @default.
- W2918789831 cites W2012997244 @default.
- W2918789831 cites W2014910413 @default.
- W2918789831 cites W2018133573 @default.
- W2918789831 cites W2020993655 @default.
- W2918789831 cites W2022607292 @default.
- W2918789831 cites W2031656809 @default.
- W2918789831 cites W2040847831 @default.
- W2918789831 cites W2044643318 @default.
- W2918789831 cites W2046939760 @default.
- W2918789831 cites W2054408680 @default.
- W2918789831 cites W2055516151 @default.
- W2918789831 cites W2056932217 @default.
- W2918789831 cites W2060456946 @default.
- W2918789831 cites W2061636315 @default.
- W2918789831 cites W2068531270 @default.
- W2918789831 cites W2071615312 @default.
- W2918789831 cites W2071667761 @default.
- W2918789831 cites W2075163141 @default.
- W2918789831 cites W2076428741 @default.
- W2918789831 cites W2092527085 @default.
- W2918789831 cites W2096433368 @default.
- W2918789831 cites W2097183047 @default.
- W2918789831 cites W2101922294 @default.
- W2918789831 cites W2103024508 @default.
- W2918789831 cites W2104311895 @default.
- W2918789831 cites W2104878678 @default.
- W2918789831 cites W2105484636 @default.
- W2918789831 cites W2106239882 @default.
- W2918789831 cites W2111302723 @default.
- W2918789831 cites W2111817932 @default.
- W2918789831 cites W2117069691 @default.
- W2918789831 cites W2119855645 @default.
- W2918789831 cites W2132963711 @default.
- W2918789831 cites W2133725650 @default.
- W2918789831 cites W2135108755 @default.
- W2918789831 cites W2142220522 @default.
- W2918789831 cites W2153220281 @default.
- W2918789831 cites W2157504125 @default.
- W2918789831 cites W2161449863 @default.
- W2918789831 cites W2164135245 @default.
- W2918789831 cites W2276727623 @default.
- W2918789831 cites W2311198707 @default.
- W2918789831 cites W2517710328 @default.
- W2918789831 cites W2568967403 @default.
- W2918789831 cites W2605571847 @default.
- W2918789831 cites W2774021923 @default.
- W2918789831 cites W2789458637 @default.
- W2918789831 cites W2798336535 @default.
- W2918789831 cites W2803519556 @default.
- W2918789831 cites W2898731911 @default.
- W2918789831 cites W2900012308 @default.
- W2918789831 cites W2952569855 @default.
- W2918789831 cites W3098227048 @default.
- W2918789831 cites W3099371268 @default.
- W2918789831 cites W3100157999 @default.
- W2918789831 cites W3100569331 @default.
- W2918789831 cites W3100892956 @default.
- W2918789831 cites W3101187304 @default.
- W2918789831 cites W3101860368 @default.
- W2918789831 cites W3101899960 @default.
- W2918789831 cites W3102013617 @default.
- W2918789831 cites W3102139407 @default.
- W2918789831 cites W3102548073 @default.
- W2918789831 cites W3102754494 @default.
- W2918789831 cites W3102784118 @default.
- W2918789831 cites W3103373000 @default.
- W2918789831 cites W3103430164 @default.
- W2918789831 cites W3103589086 @default.
- W2918789831 cites W3104240849 @default.
- W2918789831 cites W3104400054 @default.
- W2918789831 cites W3104405538 @default.
- W2918789831 cites W3105327772 @default.
- W2918789831 cites W3105502341 @default.
- W2918789831 cites W3106008382 @default.
- W2918789831 cites W3106048937 @default.
- W2918789831 cites W3124781810 @default.
- W2918789831 cites W3125043314 @default.
- W2918789831 cites W4244945807 @default.
- W2918789831 cites W4289710306 @default.