Grid of theoretical NLTE equivalent widths of four Ba II lines and barium abundance in cool stars

Abstract

We present a grid of computed non-local thermodynamic equilibrium (NLTE) equivalent widths (EW) and NLTE abundance corrections for four Ba II lines: 4554, 5853, 6141, and 6496 A. The grid can be useful in deriving the NLTE barium abundance in stars having parameters in the following ranges: effective temperature from 4000 K to 6500 K, surface gravity log g from 0 to 5, microturbulent velocity 0 km s^-1 to 3 km s^-1, metallicity [Fe/H] from -2 to +0.5, and [Ba/Fe] from -0.4 to +0.6. The NLTE abundance can be either derived by EW interpolation (using the observed Ba II line EW) or by using the NLTE correction applied to a previously determined LTE abundance. Ba II line equivalent widths and the NLTE corrections were calculated using the updated MULTI code and the Ba II atomic model that was previously applied to determine the NLTE barium abundance in different types of stars. The grid is available on-line through the web, and we find that the grid Ba NLTE corrections are almost as accurate as direct NLTE profile fitting (to within 0.05-0.08 dex). For the weakest Ba II line (5853 A) the LTE abundances almost agree with the NLTE abundances, whereas the other three Ba II lines, 4554, 6141, and 6496 A, need NLTE corrections even at the highest metallicities tested here. The 4554 A line is extremely strong and should not be used for abundance analysis above [Fe/H]= -1. Furthermore, we tested the impact of different model atmospheres and spectrum synthesis codes and found average differences of 0.06 dex and 0.09 dex, respectively, for all four lines. At these metallicities we find an average Delta NLTE of +/-0.1 dex for the three useful Ba lines for subsolar cool dwarfs.

9 pages 8 figures submitted to A&A

References in corpus (7)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• Silver and palladium help unveil the nature of a second r-process
• Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars
• The chemical composition of red giants in 47 Tucanae I: Fundamental parameters and chemical abundance patterns
• Spectroscopy of high proper motion stars in the ground--based UV

Cited by in corpus (44)

• Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry
• The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys
• High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age
• Two chemically similar stellar overdensities on opposite sides of the plane of the Galaxy
• Observational constraints on the origin of the elements II. 3D non-LTE formation of Ba ii lines in the solar atmosphere
• Ages and heavy element abundances from very metal-poor stars in the Sagittarius dwarf galaxy
• Abundances and kinematics of carbon-enhanced metal-poor stars in the Galactic halo*; A new classification scheme based on Sr and Ba
• A critical reassessment of the fundamental properties of GJ 504: Chemical composition and age
• Phosphorus-rich stars with unusual abundances are challenging theoretical predictions
• The Gaia-ESO Survey: A new approach to chemically characterising young open clusters II. Abundances of the neutron-capture elements Cu, Sr, Y, Zr, Ba, La, and Ce
• Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood
• The S2 Stream: the shreds of a primitive dwarf galaxy
• Solar twins and the Barium puzzle
• Observational constraints on the origin of the elements. VII. NLTE analysis of Y II lines in spectra of cool stars and implications for Y as a Galactic chemical clock
• Detailed chemical compositions of the wide binary HD 80606/80607: revised stellar properties and constraints on planet formation
• OCCASO V. Chemical-abundance trends with Galactocentric distance and age
• Detailed abundances from integrated-light spectroscopy: Milky Way globular clusters
• Local associations and the barium puzzle
• The chemical composition of $\alpha$ Cen AB revisited
• X-shooter spectroscopy of young stellar objects in Lupus: Lithium, iron, and barium elemental abundances
• High-precision analysis of binary stars with planets. I. Searching for condensation temperature trends in the HD 106515 system
• HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star?
• First determination of s-process element abundances in pre-main sequence clusters: Y, Zr, La, and Ce in IC 2391, the Argus association and IC 2602
• Chemically peculiar A and F stars with enhanced s-process and iron-peak elements: stellar radiative acceleration at work
• r-process Abundance Patterns in the Globular Cluster M92
• Young giants of intermediate mass Evidence of rotation and mixing
• Neutron-capture elements in dwarf galaxies I: Chemical clocks & the short timescale of the r-process
• Chemical abundances in the metal-intermediate GC NGC 6723
• $S^5$: The destruction of a bright dwarf galaxy as revealed by the chemistry of the Indus stellar stream
• 1D non-LTE corrections for chemical abundance analyses of very metal-poor stars
• NLTE modelling of integrated light spectra. Abundances of barium, magnesium, and manganese in a metal-poor globular cluster
• Evidence for multiple nucleosynthetic processes from carbon enhanced metal-poor stars in the Carina dwarf spheroidal galaxy
• High-speed stars. II. An unbound star, young stars, bulge metal-poor stars, and Aurora candidates
• Sun-like stars unlike the Sun: Clues for chemical anomalies of cool stars
• Abundances in a sample of turnoff and subgiant stars in NGC 6121 (M4)
• Neutron-capture elements in dwarf galaxies III: A homogenized analysis of 13 dwarf spheroidal and ultra-faint galaxies
• G112-43/44: A metal-poor binary star with a unique chemical composition and kinematics like the Helmi streams
• Observational constraints on the origin of the elements. IX. 3D NLTE abundances of metals in the context of Galactic Chemical Evolution Models and 4MOST
• Something borrowed, something blue: The nature of blue metal-poor stars inferred from their colours and chemical abundances
• Chemical composition of stars with massive planets
• The Gaia RVS benchmark stars II. A sample of stars selected for their Gaia high radial velocity
• Full abundance study of two newly discovered barium giants
• Heavy Elements -- They came out of the blue
• Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo