Influence of departures from LTE on determinations of the sulfur abundances in A-K type stars

Abstract

The influence of departures from local thermodynamic equilibrium (LTE) on neutral sulfur lines is considered. A grid of corrections is proposed to take into account the influence of departures from LTE for neutral sulfur lines in the visible and infrared spectral regions, including the H-band. The grid is calculated using the atomic model of sulfur incorporating the most up-to-date collision rates with electrons and hydrogen. The inclusion of levels and transitions of ionized sulfur in the atomic model made it possible to expand the range of effective temperatures of stellar photospheres in the grid up to 10000 K. The atomic model was tested in determining the sulfur abundance of 13 stars and showed its adequacy in a wide range of fundamental stellar parameters. In the spectra of all test stars, the sulfur lines are fitted with similar abundances of the element, regardless of the degree of influence of the effects of deviation from LTE on a particular spectral line. For lines of several multiplets, the wavelengths and oscillator strengths were refined. A list of S I lines recommended for determining sulfur abundance has been created.

arXiv comment14 pages, 11 figures

References in corpus (13)

• The chemical make-up of the Sun: A 2020 vision
• Evolution, Explosion and Nucleosynthesis of Core Collapse Supernovae
• New ATLAS9 And MARCS Model Atmosphere Grids for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• PolarBase: a data base of high resolution spectropolarimetric stellar observations
• Gaia FGK benchmark stars: abundances of alpha and iron-peak elements
• Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
• The IAG solar flux atlas: Accurate wavelengths and absolute convective blueshift in standard solar spectra
• Sulphur abundance in very metal-poor stars
• Accurate Fundamental Parameters or A, F, and G-type Supergiants in the Solar Neighbourhood
• First Stars XIV. Sulfur abundances in extremely metal-poor (EMP) stars
• DECH: Software Package for Astronomical Spectral Data Processing and Analysis
• The Galactic evolution of sulphur as traced by globular clusters
• Study of the departures from LTE in the unevolved stars infra-red spectra

Cited by in corpus (1)

• The solar sulphur abundance in view of large-scale atomic structure calculations and 3D non-LTE models