Atomic Diffusion and Radiative Accelerations in Stellar Atmospheres

摘要

Atomic diffusion modifies elements distributions in the atmospheres of the main-sequence chemically peculiar A and B type stars. The main ingredient in evaluating diffusion effects in atmospheres is the radiative acceleration, which accounts for the momentum transfer from the photon flux to atoms. In most cases these stars have strong magnetic fields, which make radiation transfer calculations very heavy to achieve. I will present recent works on this subject, and will present the numerical tools (from calculation of polarised radiation transfer to time-dependent elements stratification) that are developed to describe the surface of these stars.