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Article
Scandium Abundance in F–G–K Stars in a Wide Metallicity Range
A new Sc II model atom has been constructed using up-to-date atomic data. To test it, we have carried out nonlocal thermodynamic equilibrium (non-LTE) calculations for three stars with reliably determined atmo...
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Article
Influence of Collisions with Hydrogen Atoms on Non-LTE Effects for K I and Ca II in Stellar Atmospheres
We have constructed a new K I model atom using currently available atomic data. We have performed calculations for K I by abandoning the assumption of local thermodynamic equilibrium (non-LTE) for the Sun and ...
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Article
Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool Stars
The possibility of solving the problem of a discrepancy in the non-LTE abundances from Ti I and Ti II lines in metal-poor stars is investigated by applying accurate data to take into account the collisions wit...
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Article
Abundances of α-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis
The atmospheric parameters and abundances of Mg, Si, Ca, and Ti have been determined for 20 stars using the Gaia DR2 parallaxes, high-resolution spectra, and modeling of lines without assuming LTE (non-LTE mod...
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Article
Even-to-Odd Barium Isotope Ratio in Selected Galactic Halo Stars
We have improved the Ba II model atom by taking into account the excitation of transitions through collisions with hydrogen atoms with the rate coefficients from the quantum-mechanical calculations of Belyaev ...
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Article
Contribution of Type Ia Supernovae to the Chemical Enrichment of the Ultra-Faint Dwarf Galaxy Boötes I
For three stars in the ultra-faint dwarf (UFD) galaxy Boötes I we have determined the atmospheric parameters, performed a new reduction of high-resolution spectra from the Subaru archive, and derived the abund...
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Article
Influence of Inelastic Collisions with Hydrogen Atoms on Non-LTE Oxygen Abundance Determinations
We present the results of our modeling of the O I line formation under non-LTE conditions in the atmospheres of FG stars. The statistical equilibrium of O I has been calculated using Barklem’s quantum-mechanic...
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Article
Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities
We have performed statistical equilibrium calculations for Ca I–Ca II, Ti I–Ti II, and Fe I–Fe II by taking into account the nonequilibrium line formation conditions (the non-LTE approach) in model atmospheres...
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Article
Influence of inelastic collisions with hydrogen atoms on the formation of AlI and SiI lines in stellar spectra
We have performed calculations by abandoning the assumption of local thermodynamic equilibrium (within the so-called non-LTE approach) for Al I and Si I with model atmospheres corresponding to stars of spectra...
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Article
Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)
The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include...
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Article
Non-LTE sodium abundance in galactic thick- and thin-disk red giants
The non-LTE sodium abundance has been determined from the Na I 6154 and 6161 Å lines for 38 thin-disk stars (15 of them are Ba II stars), 15 thick-disk stars, 13 Hercules-stream stars, and 13 stars that cannot...
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Article
Influence of departures from LTE on oxygen abundance determination in the atmospheres of A-K stars
We have performed non-LTE calculations for O I with a multilevel model atom using currently available atomic data for a set of parameters corresponding to stars of spectral types from A to K. Departures from L...
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Article
The r- and s-process contributions to heavy-element abundances in the halo star HD 29907
The abundances of 22 heavy elements from Sr to Pb have been determined for the halo star HD 29907 (T eff = 5500 K, log g = 4.64) with [Fe/H] = −1.55 using high-quality VLT/UVES spectra (ES...
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Article
Erratum to: “Formation of Zr I and Zr II Lines under NON-LTE Conditions of Stellar Atmospheres”
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Article
Formation of Zr I and II lines under non-LTE conditions of stellar atmospheres
The formation of Zr I and Zr II lines in stellar atmospheres under non-LTE conditions has been considered for the first time. A model zirconium atom has been composed using 148 Zr I levels, 772 Zr II levels, a...
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Article
Neutron-capture elements in halo, thick-disk, and thin-disk stars. Strontium, yttrium, zirconium, cerium
We derived Sr, Y, Zr, and Ce abundances for a sample of 74 cool dwarfs and subgiants with iron abundances, [Fe/H], between 0.25 and −2.43. These estimates were obtained using synthetic spectra, assuming local ...
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Article
The atmospheric lithium abundances of solar analogues
We have analyzed the lithium abundance in the atmospheres of 20 stars that are solar analogues based on high-resolution echelle spectra using model atmospheres in a non-LTE approach. In terms of their lithium ...
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Article
Neutron-capture elements in halo, thick-disk, and thin-disk stars: Neodymium
We have derived the LTE neodymium abundances in 60 cool stars with metallicities [Fe/H] from 0.25 to −1.71 by applying a synthetic-spectrum analysis to spectroscopic observations of NdII lines with a resolutio...
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Article
Effects of spot structure of lines of rare earths and non-LTE effects on lithium abundance estimates for two roAp stars
Taking into account blending of the lithium 6108 Å line profile by adjacent rare-earth lines together with their spotted surface structure does not appreciably affect lithium abundance estimates for the atmosp...
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Article
Eu III oscillator strengths and europium abundances in Ap stars
We present our calculations of the spectrum and oscillator strengths for the 4f7−(4f65d+4f66s) Eu III transitions. The calculations were performed with Cowan's RCN-RCG-RCE codes in the single-configuration approx...
