| The purpose of this investigation is the development of an accurate NLTE theory for the transport of polarized radiation in spectral lines with the inclusion of partial frequency redistribution of photons in the scattering process.;In Chapter 2, a NLTE theory for the transport of polarized radiation in spectral lines is derived, and is tested for lines formed in isothermal atmospheres. This method is shown to be an extremely flexible method for the solution of the transfer equation. The technique described is a direct extension of the moment equation method developed by Collins (Astrophys. J. 175, p. 147, 1972).;In Chapter 3, the theoretical line profiles and polarization structures for the KI(lamda)7699(ANGSTROM), SrI(lamda)4607(ANGSTROM), BaII(lamda)4554(ANGSTROM), and CaI(lamda)4227(ANGSTROM) lines are computed for solar atmospheric conditions. The line line profiles and polarization structures for these solar lines agree well with the observations of Stenflo et al. (Astron. Astrophys. 80, p. 60, 1980). For the weak lines, a linear combination of R(,II) and R(,III) is used. For the strong resonance line CaI(lamda)4277(ANGSTROM), this redistribution function does not reproduce the observed polarization spike at line center. When R(,V) is used, the gross characteristics of the polarization structure, in particular the polarization spike at line center, are reproduced.;In Chapter 4, the emergent polarization in the MgII(lamda)4481(ANGSTROM) doublet and in H(gamma) for the two rapidly rotating B5V stars (w = 0.5 and w = 0.9) is computed. For the MgII(lamda)4481(ANGSTROM) doublet, the emergent polarization is negligible for both rapidly rotating stars for all inclinations of the rotational axis. The H(gamma) polarization is, however, a measurable quantity for the i = 90(DEGREES), w = 0.9 case. There is a clear separation of the polarization maxima as the inclination of the system is varied. Using data from other spectral lines, it may be possible to determine the inclination of the rotational axis of the rapidly rotating stars, and ultimately the geometry of the emitting region. This will allow for tests of the stellar interior calculations for rapidly rotating stars.;First, however, the nature of the scattering process and the forms of the redistribution functions for model two-level atoms are discussed. The methods for the evaluation of R(,I), R(,II), and R(,III) are derived, and R(,V), the redistribution function for a two-level atom which has both levels broadened by radiation and collisions (in the impact approximation), is derived and discussed. It is seen that R(,V) for scattering at 4 or 5 doppler widths from line center has coherent and completely redistributed components of about the same magnitude. Furthermore, near line center, the scattering also has a strong coherent component. For two doppler widths from line center, the scattering is well approximated by complete redistribution. |
