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Astron. Astrophys. 360, 1086-1095 (2000)

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Profiles of the spectral lines formed in stochastic multicomponent atmosphere

A.G. Nikoghossian 1,2 and Z. Mouradian 2

1 Byurakan Astrophysical Observatory, Isaac Newton Institute of Chile, Armenian Branch, 378433 Byurakan, Armenia
2 Observatoire de Paris-Meudon, DASOP, 92195 Meudon Cedex, France

Received 23 November 1999 / Accepted 11 April 2000

Abstract

An analytical procedure is explored to construct the profiles of the spectral lines formed in a stochastic multicomponent atmosphere. A model one-dimensional problem is solved for the atmospheres in both local thermodynamic equilibrium (LTE) and non-LTE. The results previously obtained by the authors for the LTE atmosphere are generalized to include, in particular, correlations of the random variations in the physical properties of the structural elements. It is shown that the stochastic multicomponent atmosphere may produce a kind of double-peaked profile, which is usually associated with the multiple scattering effects.

The problem of the line formation in a stochastic non-LTE atmosphere is considered, assumpting the complete redistribution over frequencies with allowance for the absorption in continuum. For the line profile, a closed-form analytical expression is derived. The computed profiles are compared with those for an homogeneous deterministic atmosphere with preliminarily averaged physical properties. This allows us to conclude that the discrepancy between the line profiles relevant to these two cases may become significant, whereas the normalized profiles are fairly close to each other.

Key words: radiative transfer – Sun: atmosphere – Sun: prominences – stars: atmospheres

Send offprint requests to: Z. Mouradian

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© European Southern Observatory (ESO) 2000

Online publication: August 23, 2000
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