Non-LTE radiative transfer in cool stars. Theory and applications to the abundance analysis for 24 chemical elements

Abstract

The interpretation of observed spectra of stars in terms of fundamental stellar properties is a key problem in astrophysics. For FGK-type stars, the radiative transfer models are often computed using the assumption of local thermodynamic equilibrium (LTE). Its validity is often questionable and needs to be supported by detailed studies, which build upon the consistent framework of non-LTE. In this review, we outline the theory of non-LTE. The processes causing departures from LTE are introduced qualitatively by their physical interpretation, as well as quantitatively by their impact on the models of stellar spectra and element abundances. We also compile and analyse the most recent results from the literature. In particular, we examine the non-LTE effects for 24 chemical elements for six late-studied FGK-type stars.

19 pages, accepted for publication as a chapter in "Determination of Atmospheric Parameters of B, A, F and G Type Stars", Springer (2014), eds. E. Niemczura, B. Smalley, W. Pych

References in corpus (6)

• NLTE abundances of Mn in a sample of metal-poor stars
• A non-LTE study of neutral and singly-ionized calcium in late-type stars
• The lithium isotopic ratio in very metal-poor stars
• Non-LTE line formation for heavy elements in four very metal-poor stars
• NLTE study of scandium in the Sun
• The non-LTE line formation of neutral carbon in late-type stars

Cited by in corpus (11)

• KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars
• High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
• The Chemical Composition of the Galactic Bulge and Implications for its Evolution
• 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
• Chemical Properties of the Local Disk and Halo. II. Abundances of 3745 M dwarfs and Subdwarfs from Improved Model Fitting of Low-Resolution Spectra
• Sun-like stars unlike the Sun: Clues for chemical anomalies of cool stars
• Observational constraints on the origin of the elements. IX. 3D NLTE abundances of metals in the context of Galactic Chemical Evolution Models and 4MOST
• Probing 3D and NLTE models using APOGEE observations of globular cluster stars
• NLTE abundances of Eu for a sample of metal-poor stars in the Galactic Halo and Metal-poor Disk with 1D and <3D> models
• Differential abundance analysis of Procyon and Theta Sculptoris: Comparison with abundance patterns of solar-like pairs
• Investigating non-LTE abundances of Neodymium (Nd) in metal-poor FGK stars