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Related papers: Basics of the NLTE physics

200 papers

We present the results of realistic, 3D, hydrodynamical, simulations of surface convection in red giant stars with varying effective temperatures and metallicities. We use the convection simulations as time-dependent, hydrodynamical, model…

Astrophysics · Physics 2007-11-21 R. Collet , M. Asplund , R. Trampedach

Accurately known stellar lithium abundances may be used to shed light on a variety of astrophysical phenomena such as Big Bang nucleosynthesis, radial migration, ages of stars and stellar clusters, and planet engulfment events. We present a…

Solar and Stellar Astrophysics · Physics 2020-10-30 E. Wang , T. Nordlander , M. Asplund , A. M. Amarsi , K. Lind , Y. Zhou

We present new detailed NLTE calculations for model atmospheres of novae during outburst. This fully self-consistent NLTE treatment for a number of model atoms includes 3922 NLTE levels and 47061 NLTE primary transitions. We discuss the…

Astrophysics · Physics 2009-10-30 Peter H. Hauschildt , Steven N. Shore , Greg J. Schwarz , E. Baron , S. Starrfield

The NLTE effects affecting oxygen-abundance determinations of solar-type stars are discussed. LTE is perfectly safe for the forbidden lines. The permitted triplet at 777 nm is expected to show NLTE effects on the order of a few tenths of a…

Astrophysics · Physics 2009-10-31 Dan Kiselman

Using the method termed complex asteroseismology, we derive constraints on model atmospheres, in particular, on the NLTE effects. We fit simultaneously pulsational frequencies and the corresponding values of the nonadiabatic complex…

Solar and Stellar Astrophysics · Physics 2012-05-18 Wojciech Szewczuk , Przemysław Walczak , Jadwiga Daszyńska-Daszkiewicz

We use the kinetic theory of nucleation to explore the properties of dust nucleation in sub-saturated vapors. Due to radiation losses, the sub-critical clusters have a smaller temperature compared to their vapor. This alters the dynamical…

Astrophysics · Physics 2015-05-13 Davide Lazzati

We describe in detail the implementation of a simplified approach to radiative transfer in general relativity by means of the well-known neutrino leakage scheme (NLS). In particular, we carry out an extensive investigation of the properties…

General Relativity and Quantum Cosmology · Physics 2013-10-03 Filippo Galeazzi , Wolfgang Kastaun , Luciano Rezzolla , José A. Font

Rate coefficients for inelastic collisions between Li and H atoms covering all transitions between the asymptotic states Li(2s,2p,3s,3p,3d,4s,4p,4d,4f)+H(1s) and Li^+ +H^- are presented for the temperature range 2000-8000 K based on recent…

Astrophysics · Physics 2009-11-10 P. S. Barklem , A. K. Belyaev , M. Asplund

In general relativity static gaseous atmospheres may be in hydrostatic balance in the absence of a supporting stellar surface, provided that the luminosity is close to the Eddington value. We construct analytic models of optically thin,…

High Energy Astrophysical Phenomena · Physics 2016-01-11 M. Wielgus , W. Kluźniak , A. Sądowski , R. Narayan , M. Abramowicz

We establish the extended formalism for description of the static spherically symmetric relativistic non-equilibrium stellar systems in the formation of which the radiation pressure plays the key role. The main concept of this extended…

General Relativity and Quantum Cosmology · Physics 2022-06-09 Alexander B. Balakin , Zagir Z. Tukbaev

We come back to the analytical solution of the standard transfer problem in a stellar atmosphere. It consists in solving the radiative transfer equation in a homogeneous and isothermal plane-parallel atmosphere, with light scattering taken…

Astrophysics · Physics 2007-05-23 L. Chevallier , B. Rutily

Methods to determine abundances of the elements in the atmospheres of F, G, and K stars with precisions of 0.01-0.03 dex are reviewed. Such high-precision stellar abundances have led to the discovery of unexpected phenomena and relations…

Solar and Stellar Astrophysics · Physics 2018-11-06 Poul Erik Nissen , Bengt Gustafsson

Aiming at testing the validity of our magnesium atomic model and investigating the effects of non-local thermodynamical equilibrium (NLTE) on the formation of the H-band neutral magnesium lines, we derive the differential Mg abundances from…

Solar and Stellar Astrophysics · Physics 2017-01-25 Junbo Zhang , Jianrong Shi , Kaike Pan , Carlos Allende Prieto , Chao Liu

In an attempt to model the accretion onto a neutron star in low-mass X-ray binaries, we present two-dimensional hydrodynamical models of the gas flow in close vicinity of the stellar surface. First we consider a gas pressure dominated case,…

Astrophysics · Physics 2009-11-13 N. Babkovskaia , A. Brandenburg , J. Poutanen

A new model atom of nitrogen was developed using the energy levels of N I from laboratory measurements and also predicted in atomic structure calculations and the most up-to-date atomic data for computing radiative and collisional rates of…

Solar and Stellar Astrophysics · Physics 2024-06-18 L. I. Mashonkina , T. A. Ryabchikova

Statistical mechanics harmonizes mechanical and thermodynamical quantities, via the notion of local thermodynamic equilibrium (LTE). In absence of external drivings, LTE becomes equilibrium tout court, and states are characterized by…

Statistical Mechanics · Physics 2018-07-25 Claudio Giberti , Lamberto Rondoni , Cecilia Vernia

It has previously been shown that it is more general to describe the evolution of the universe based on the emergence of the space and the energy balance relation. Here we investigate the thermodynamic properties of the universe described…

General Relativity and Quantum Cosmology · Physics 2019-03-27 Fei-Quan Tu , Yi-Xin Chen , Qi-Hong Huang

The equilibrium of dense plasma in a self-gravitation is considered. The obtained results radically distinguish from the point of view which is commonly accepted in the astrophysical society. It is important that all these results were…

Astrophysics · Physics 2007-05-23 B. V. Vasiliev

We present atmospheric models of red giant stars of various metallicities, including extremely metal poor (XMP, [Fe/H]<-3.5) models, with many chemical species, including, significantly, the first two ionization stages of Strontium (Sr) and…

Astrophysics · Physics 2009-11-11 C. I. Short , P. H. Hauschildt

We present accurate methods of abundance determination based on the non-local thermodynamic equilibrium (NLTE) line formation for carbon, oxygen, calcium, titanium, and iron in the atmospheres of BAF-type stars. For C I-II, O I, Ca I-II,…

Solar and Stellar Astrophysics · Physics 2018-08-22 Tatyana Sitnova , Tatyana Ryabchikova , Sofya Alexeeva , Lyudmila Mashonkina