Review: progress in NLTE calculations and their application to large data-sets

Abstract

One of the major tasks in interpretation of data from large-scale stellar surveys is to determine the fundamental atmospheric parameters such as effective temperature, surface gravity, and metallicity. In most on-going and upcoming projects, they are derived spectroscopically, with relying on classical one-dimensional (1D) model atmospheres and the assumption of LTE. This review discusses the present achievements and problems of non-local thermodynamic equilibrium (NLTE) line-formation calculations for FGK-type stars. The topics that are addressed include (i) the construction of comprehensive model atoms for the chemical elements with complex term system, (ii) possible systematic errors inherent in classical LTE spectroscopic determinations of stellar parameters and chemical abundances, (iii) the uncertainties in final NLTE results caused by the uncertainties in atomic data, and (iv) applications of the NLTE line-formation calculations coupled to the spatial and temporal average <3D> models to spectroscopic analyses.

11 pages. To appear in Proceedings of the IAU Symposium No. 298, "Setting the scene for Gaia and LAMOST", eds. S. Feltzing, G. Zhao, N. A. Walton, and P. A. Whitelock

References in corpus (5)

• NLTE line formation of Fe for late-type stars. I. Standard stars with 1D and <3D> model atmospheres
• NLTE line formation of Fe in late-type stars II: 1D spectroscopic stellar parameters
• HE 0557-4840 - Ultra-Metal-Poor and Carbon-Rich
• Unveiling systematic biases in 1D LTE excitation-ionisation balance of Fe for FGK stars. A novel approach to determination of stellar parameters
• Improving the Ni I atomic model for solar and stellar atmospheric models

Cited by in corpus (4)

• The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment
• Abundances in the Local Region I: G and K Giants
• A new algorithm for optimizing the wavelength coverage for spectroscopic studies: Spectral Wavelength Optimization Code (SWOC)
• Probing 3D and NLTE models using APOGEE observations of globular cluster stars