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Models of the Solar Atmosphere

  • P. Heinzel
Conference paper
Part of the NATO Science Series book series (ASIC, volume 558)

Abstract

Among the atmospheres of different stars, the solar atmosphere has a privilege to provide us an insight into various structural patterns and their dynamical behaviour. While most of stellar atmospheres are simply modelled as one-dimensional (1D) plane-parallel or spherically-symmetrical layer, the solar atmosphere must generally be resolved into various brightness components which also exhibit quite different behaviour. Therefore, a single solar atmospheric model cannot in general be treated as horizontally homogeneous, although historically this was the first step in modelling. While many stars have just the photospheres, the Sun - like some other stars - possesses also the chromosphere and the corona. The coronal temperatures reach millions degrees within very narrow chromosphere-corona transition region (CCTR) where steep temperature gradients allow an efficient heat conduction down to the lower layers of CCTR. The presence of these external layers largely complicates the solar atmospheric modelling at least for two reasons. First, due to their low density, strong departures from local thermodynamic equilibrium (LTE) exist. This is the principal problem which requires much more complicated so-called NLTE (or non-LTE) treatment of the radiative transfer. In fact, the solar atmosphere served as a ‘test laboratory’ for a development of basic concepts of NLTE theory in late fifties and early sixties (see [2]).

Keywords

Solar Atmosphere Local Thermodynamic Equilibrium Stellar Atmosphere Ambipolar Diffusion Semiempirical Model 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2000

Authors and Affiliations

  • P. Heinzel
    • 1
  1. 1.Astronomical InstituteAcademy of Sciences of the Czech RepublicOndřejovCzech Republic

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