The generation and transfer of polarized radiation in stellar atmospheres

This paper addresses the modeling issue of spectral line polarization in stellar atmospheres, taking into account scattering processes and the Hanle and Zeeman effects in two-level and multilevel atomic models, and with the statistical equilibrium and radiative transfer equations formulated within the framework of the quantum theory of polarization. After arguing why this research field is of real astrophysical interest, the basic equations and anisotropic pumping mechanisms are reviewed. Finally, it is shown how to solve efficiently a variety of polarization transfer problems via the application of fast iterative methods and accurate formal solvers of the Stokes vector transfer equation.