New radiative transfer diagnostic techniques: from proto-planetary disks to the Sun

Radiative transfer is a fundamental tool for the analysis of astronomical observations.
Although the theoretical foundations of the basic problem of radiative transfer are widely known, we still witness improvements in the tools used to solve the equations. Furthermore, polarized radiative transfer is becoming of great interest due to the availability of very sensitive spectro-polarimeters. In this seminar I discuss some recent advances that we have obtained in the field: the prediction of the capabilities of ALMA to observe the H2D+ line emission in proto-planetary disks, the development of new diagnostic techniques for the study of the magnetism of the quiet Sun and the application of observations of scattering polarization in helium multiplets to investigate magnetized plasmas in solar and stellar chromospheres.