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
1
Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic e-mail: stepan@asu.cas.cz
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
Received:
4
October
2006
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