| |
*Astron. Astrophys. 328, 726-751*
**Available formats:** HTML |
PDF |
(gzipped) PostScript
## Master equation theory applied to the redistribution
of polarized radiation, in the weak radiation field limit
### II. Arbitrary magnetic field case
**V. Bommier**
Laboratoire `Atomes et Molécules en Astrophysique',
CNRS URA 812 - DAMAp, Observatoire de Paris, Section de Meudon, F-92195
Meudon, France (Veronique.Bommier@obspm.fr)
*Received 11 February 1997 / Accepted 4 August 1997*
**Abstract**
This paper addresses the problem of partial redistribution of
polarized radiation in the presence of a magnetic field of arbitrary
strength. It is the continuation of a previous paper (Paper I)
devoted to the same problem, treated in the simpler case of vanishing
magnetic field. In the present paper, we give the results of the
derivation of the master equation for the atomic density matrix, and
of the coefficients of the radiative transfer equation, following the
method described in Paper I (which makes use of the summation
of the perturbation series development for the atom-radiation
interaction), now applied to the case of a non-zero magnetic field of
arbitrary strength. The other hypotheses underlying the derivation of
Paper I are maintained in the present paper, namely: (a) weak
radiation field (stimulated emission is neglected with respect to
spontaneous emission); (b) 2-level atom; (c) unpolarized lower level.
The redistribution matrix, that relates the frequency, polarization
and direction of the incident photon to those of the scattered photon,
is derived in the presence of a magnetic field of arbitrary strength.
3 successive levels of approximation are proposed, in the case of a
weak magnetic field, in order to derive simpler expressions for the
redistribution matrix that might conveniently be used in radiative
transfer calculations.
**Key words: **atomic processes - line: formation - line: profiles -
magnetic fields - polarization - radiative transfer
© European Southern Observatory (ESO) 1997
Online publication: November 24, 1997
Last change: March 26, 1998
helpdesk.link@springer.de |