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Related papers: Full non-LTE spectral line formation I. Setting th…

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In this paper we discuss numerical methods and algorithms for the solution of NLTE stellar atmosphere problems involving expanding atmospheres, e.g., found in novae, supernovae and stellar winds. We show how a scheme of nested iterations…

Astrophysics · Physics 2011-06-02 P. H. Hauschildt , E. Baron

We investigate the non-Local Thermodynamic Equilibrium (non-LTE) line formation of neutral carbon in late-type stars in order to remove some of the potential systematic errors in stellar abundance analyses employing C I features. The…

Astrophysics · Physics 2009-11-11 D. Fabbian , M. Asplund , M. Carlsson , D. Kiselman

We performed non-LTE calculations for O I with the plane-parallel model atmospheres for a set of stellar parameters corresponding to A-K type stars. The model atom of Przybilla et al. (2000) was updated using the best theoretical and…

Solar and Stellar Astrophysics · Physics 2013-02-06 T. M. Sitnova , L. I. Mashonkina , T. A. Ryabchikova

The formation of the resonance lines of neutral boron in solar-type stellar atmospheres is investigated taking into account effects of departures from local thermodynamic equilibrium (NLTE effects). The latter are due to a combination of…

Astrophysics · Physics 2007-05-23 Dan Kiselman

NLTE effects - the errors caused by assuming local thermodynamic equilibrium (LTE) - on LiBeB abundance determinations for cool stars are discussed. These NLTE effects are significant in many cases for B I and Li I lines. The Be II 313 nm…

Astrophysics · Physics 2007-05-23 Dan Kiselman

Based on detailed 2D radiation hydrodynamics (RHD) simulations, we have investigated the effects of photospheric temperature inhomogeneities induced by convection on spectroscopic determinations of the lithium abundance. Computations have…

Astrophysics · Physics 2007-05-23 R. Cayrel , M. Steffen

Superstatistics (Physica A 322, 267-275, 2003) is a formalism that attempts to explain the presence of distributions other than the Boltzmann-Gibbs distributions in Nature, typically power-law behavior, for systems out of equilibrium such…

Statistical Mechanics · Physics 2019-02-27 Sergio Davis , Gonzalo Gutiérrez

In this review we discuss possible systematic errors inherent in classical 1D LTE abundance analyses of late-type stars for the light elements (here: H, He, Li, Be and B). The advent of realistic 3D hydrodynamical model atmospheres and the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Martin Asplund , Karin Lind

An analytical theory is developed for radiationless transitions in molecules characterized by nonequilibrium populations of their vibrational modes. Several changes to the standard transition-state framework follow from nonequilibrium…

Chemical Physics · Physics 2019-03-27 Dmitry V. Matyushov

Earlier studies have suggested that deviations from the local thermodynamic equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. Recent improvements in the atomic data allow…

Solar and Stellar Astrophysics · Physics 2022-01-12 S. Korotin , A. Kučinskas

Inferring the coupling of different atmospheric layers requires observing spectral lines sensitive to the atmospheric parameters, particularly the magnetic field vector, at various heights. The best way to tackle this goal is to perform…

Aims: Hydrogen and helium line spectra are crucial diagnostic features for the quantitative analysis of OB stars. We compute synthetic spectra based on a hybrid non-LTE approach in order to test the ability of these models to reproduce…

Astrophysics · Physics 2009-11-11 M. F. Nieva , N. Przybilla

We investigate departures from LTE in the line formation of Fe for a number of well-studied late-type stars in different evolutionary stages. A new model of Fe atom was constructed from the most up-to-date theoretical and experimental…

Solar and Stellar Astrophysics · Physics 2015-06-05 Maria Bergemann , Karin Lind , Remo Collet , Zazralt Magic , Martin Asplund

This study concerns the fast and accurate solution of multilevel non-LTE radiation transfer problems. We propose and evaluate an alternative iterative scheme to the classical MALI method. Our study is indeed based on the application of…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 S. Nicolas , L. Bigarré , F. Paletou

Nonequilibrium thermodynamics has shown its applicability in a wide variety of different situations pertaining to fields such as physics, chemistry, biology, and engineering. As successful as it is, however, its current formulation…

Condensed Matter · Physics 2009-11-07 J. M. G. Vilar , J. M. Rubi

We present a study of departures from Local Thermodynamic Equilibrium (LTE) in the formation of infra-red lines of Na I, Mg I, Al I, S I, K I and Sr II in unevolved stars of spectral types F,G,K and metallicities around the solar…

Solar and Stellar Astrophysics · Physics 2020-06-22 S. A. Korotin , S. M. Andrievsky , E. Caffau , P. Bonifacio , E. Oliva

High-energy, multi-component plasmas in which pair creation and annihilation, lepton-lepton scattering, lepton-proton scattering, and Comptonization all contribute to establishing the particle and photon distributions, are present in a…

Astrophysics · Physics 2014-10-13 Sergei Nayakshin , Fulvio Melia

A self-consistent nonlinear hydrodynamic theory is presented of the propagation of a long and thin relativistic electron beam through a plasma that is relatively strongly magnetized, $|\Omega_e|\sim\omega_{pe}$ and whose density is much…

Plasma Physics · Physics 2018-07-04 Dusan Jovanovic , Renato Fedele , Milivoj Belic , Sergio De Nicola

We develop a non-equilibrium field-theoretical approach, based on a systematic diagrammatic expansion, for strongly interacting photons in optically dense atomic media. We consider the case where the characteristic photon-propagation range…

Quantum Gases · Physics 2021-01-19 Johannes Lang , Darrick E. Chang , Francesco Piazza

Many classes of non-parity-time (PT) symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this article, nonlinear light behaviors in these complex waveguides…

Optics · Physics 2016-06-29 Sean Nixon , Jianke Yang