Towards consistent stellar magnetic atmospheres

The proposed research topic is directly connected with fundamental, but still unsolved problems of modern astrophysics: the generation and evolution of magnetic fields of the vast majority of stars observable in the Universe - stars in the core Hydrogen burning, Main Sequence evolutionary phase. Presently, two schools advocate contradicting models based on a fossil field theory on the one hand and on the generation of magnetic fields inside the stars via the dynamo mechanisms on the other hand. To work on solving this problem I intend to obtain high-resolution spectra of magnetic stars in polarized and un-polarized light which will allow determining the surface magnetic field structure, or derive tight limits for it. The primary goal is to infer from such structures the internal field configurations for magnetic MS stars. Finally, a well chosen sample of such stars shall allow drawing conclusions about the evolution of magnetic fields in stars that have arrived at the ZAMS till the end of core Hydrogen burning, hence dealing with a sample which represents the most numerous component of our Universe directly observable from ground. A secondary goal is to investigate and to study in detail the effects of stratification (diffusion) of different elements in stellar atmospheres. This knowledge is mandatory for determining precisely the global abundance of chemical elements in stars and to model correctly their evolution. Magnetic field effects will have to be included in such investigations wherever such a field is being observed - or has to be expected to be significant. The result of the proposed project shall be a new generation of physically more consistent models concerning the chemical structure of stars and in particular their atmosphere, structure and evolution of stellar magnetic fields, evolution of chemical elements in their atmospheres and the efficiency of different physical mechanisms leading to the separation of different elements. Such new models are relevant also for understanding the chemical evolution of our Universe. Hence, research makes use of stars as perfect laboratories for chemical and physical processes of which some of them can only be studied the way I propose. Chemically peculiar and magnetic (CP) stars will be prime targets for this investigation as they show an inhomogeneous abundances distribution over the stellar surface as well as along the stellar radius. In addition, some of the CP stars have large-scale stable magnetic fields with different intensities. These stars allow isolating - and hence to study in detail - the effects of magnetic fields, stratification in atmospheres and of still unsolved other problems, like microscopic processes of atomic and ionic diffusion, evolution and stability of global magnetic fields and the role of Lorentz forces.