Search Results - "Sitnova, T M"

A non-local thermodynamical equilibrium line formation for neutral and singly ionized titanium in model atmospheres of reference A–K stars by Sitnova, T. M., Mashonkina, L. I., Ryabchikova, T. A.

“…We construct a model atom for Ti i–ii using more than 3600 measured and predicted energy levels of Ti i and 1800 energy levels of Ti ii, and quantum mechanical…”
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Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions by Sitnova, T M, Yakovleva, S A, Belyaev, A K, Mashonkina, L I

“…ABSTRACT We present a new model atom of Zn i-Zn ii based on the most up-to-date photoionization cross-sections, electron-impact excitation rates, and rate…”
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A NLTE line formation for neutral and singly ionized calcium in model atmospheres of B-F stars by Sitnova, T M, Mashonkina, L I, Ryabchikova, T A

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Ultra metal-poor stars: improved atmospheric parameters and NLTE abundances of magnesium and calcium by Sitnova, T M, Mashonkina, L I, Ezzeddine, R, Frebel, A

“…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…”
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Non-LTE abundance analysis of A-B stars with low rotational velocities – II. Do A-B stars with normal abundances exist? by Romanovskaya, A M, Ryabchikova, T A, Pakhomov, Yu V, Korotin, S A, Sitnova, T M

“…ABSTRACT We present chemical composition and fundamental parameters (the effective temperature, surface gravity, and radius) for four sharp-lined A-type stars…”
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Evolution of the titanium and oxygen abundances from observations of FGK dwarfs in a wide metallicity range by Sitnova, T. M.

“…For a sample of dwarf stars close to the Sun with well-known atmospheric parameters and an iron abundance in the range −2.6 < [Fe/H] < 0.2, we have determined…”
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The Pristine survey – XXII. A serendipitous discovery of an extremely Li-rich very metal-poor giant and a new method of 6Li/7Li isotope measurement by Sitnova, T M, Matsuno, T, Martin, N F, Banerjee, P, Sestito, F, Venn, K A, González Hernández, J I

“…ABSTRACT We report the serendipitous discovery of a very metal-poor (VMP) Li-rich giant star (Teff = 4690 ± 80 K, log g = 1.34 ± 0.13, [Fe/H] = −2.43 ± 0.07)…”
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The formation of the milky way halo and its dwarf satellites: a NLTE-1D abundance analysis. IV. Segue 1, Triangulum ii, and Coma Berenices UFDs by Sitnova, T M, Mashonkina, L I, Tatarnikov, A M, Voziakova, O V, Burlak, M A, Pakhomov, Yu V, Jablonka, P, Neretina, M D, Frebel, A

“…ABSTRACT We present atmospheric parameters and abundances for chemical elements from carbon to barium in metal-poor stars in Segue 1 (seven stars), Coma…”
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Influence of Inelastic Collisions with Hydrogen Atoms on Non-LTE Oxygen Abundance Determinations by Sitnova, T. M., Mashonkina, L. I.

“…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…”
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Abundances of α-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis by Mashonkina, L. I., Neretina, M. D., Sitnova, T. M., Pakhomov, Yu. V.

“…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…”
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Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool Stars by Sitnova, T. M., Yakovleva, S. A., Belyaev, A. K., Mashonkina, L. I.

“…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…”
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Influence of Collisions with Hydrogen Atoms on Non-LTE Effects for K I and Ca II in Stellar Atmospheres by Neretina, M. D., Mashonkina, L. I., Sitnova, T. M., Yakovleva, S. A., Belyaev, A. K.

“…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…”
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Influence of departures from LTE on oxygen abundance determination in the atmospheres of A-K stars by Sitnova, T. M., Mashonkina, L. I., Ryabchikova, T. A.

“…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…”
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Contribution of Type Ia Supernovae to the Chemical Enrichment of the Ultra-Faint Dwarf Galaxy Boötes I by Pakhomov, Yu. V., Mashonkina, L. I., Sitnova, T. M., Jablonka, P.

“…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…”
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Non-LTE modeling of narrow emission components of He and Ca lines in optical spectra of classical T Tauri stars by Dodin, A. V., Lamzin, S. A., Sitnova, T. M.

“…Using LTE calculations of the structure of T Tauri stellar atmospheres heated by radiation from an accretion shock (Dodin and Lamzin 2012), we have calculated…”
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The r- and s-process contributions to heavy-element abundances in the halo star HD 29907 by Sitnova, T. M., Mashonkina, L. I.

“…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…”
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Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions by Sitnova, T. M, Yakovleva, S. A, Belyaev, A. K, Mashonkina, L. I

“…We present a new model atom of Zn I-II based on the most up-to-date photoionisation cross-sections, electron-impact excitation rates, and rate coefficients for…”
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Contribution of type Ia supernovae to the chemical enrichment of the ultra-faint dwarf galaxy Bootes I by Pakhomov, Yu. V, Mashonkina, L. I, Sitnova, T. M, Jablonka, P

“…ISSN 1063-7737, Astronomy Letters, 2019, 45, 259-275 For three stars in the ultra-faint dwarf (UFD) galaxy Bootes I we have determined the atmospheric…”
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Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool Stars by Sitnova, T. M, Yakovleva, S. A, Belyaev, A. K, Mashonkina, L. I

“…We performed the non-local thermodynamic equilibrium (non-LTE) calculations for Ti I-II with the updated model atom that includes quantum-mechanical rate…”
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The formation of the Milky Way halo and its dwarf satellites: a NLTE-1D abundance analysis. IV. Segue 1, Triangulum II, and Coma Berenices UFDs by Sitnova, T. M, Mashonkina, L. I, Tatarnikov, A. M, Voziakova, O. V, Burlak, M. A, Pakhomov, Yu. V, Jablonka, P, Neretina, M. D, Frebel, A

“…We present atmospheric parameters and abundances for chemical elements from carbon to barium in metal-poor stars in Segue 1 (seven stars), Coma Berenices…”
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