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NLTE Radiative Transfer in Cool Stars

Theory and Applications to the Abundance Analysis for 24 Chemical Elements
  • Maria Bergemann
  • Thomas Nordlander
Chapter
Part of the GeoPlanet: Earth and Planetary Sciences book series (GEPS)

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 NLTE. In this review, we outline the theory of NLTE. 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 NLTE effects for 24 chemical elements for six well-studied FGK-type stars.

Keywords

Line: formation Radiation mechanisms: general Radiative transfer Stars: atmospheres Stars: late-type 

Notes

Acknowledgments

Figure 3 has been kindly provided by Rob Rutten; http://www.staff.science.uu.nl/~rutte101.

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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  1. 1.Institute of AstronomyUniversity of CambridgeCambridgeUK
  2. 2.Division of Astronomy and Space Physics, Department of Physics and AstronomyUppsala UniversityUppsalaSweden

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