A generalized -law
The role of unphysical source terms in resonance line polarization transfer and its importance as an additional test of NLTE radiative transfer codes
Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic e-mail: email@example.com
2 LERMA, Observatoire de Paris–Meudon, CNRS UMR 8112, 5 place Jules Janssen, 92195 Meudon Cedex, France e-mail: [jiri.stepan;V.Bommier]@obspm.fr
Accepted: 26 March 2007
Context.A derivation of a generalized -law for nonthermal collisional rates of excitation by charged perturbers is presented.
Aims.Aim of this paper is to find a more general analytical expression for a surface value of the source function which can be used as an additional tool for verification of the non-LTE radiative transfer codes.
Methods.Under the impact approximation hypothesis, static, one-dimensional, plane-parallel atmosphere, constant magnetic field of arbitrary strength and direction, two-level atom model with unpolarized lower level and stimulated emission neglected, we introduce the unphysical terms into the equations of statistical equilibrium and solve the appropriate non-LTE integral equations.
Results.We derive a new analytical condition for the surface values of the source function components expressed on the basis of irreducible spherical tensors.
Key words: line: formation / polarization / radiative transfer
© ESO, 2007