On some regularities of chemical composition distribution in stellar atmospheres

The study of element abundances in the solar atmosphere and in the outer stellar atmospheres is of substantial interest, since their distribution greatly influences the composition of interstellar medium and, therefore, the star formation. In the atmospheres of stars of different spectral types and in the solar atmosphere, the element abundance distribution is inhomogeneous and is determined by the physical effect connected with the value of the first ionization potential (FIP-effect). We present the review of modern observational results of element abundance distribution in the solar and stellar atmospheres. We discuss the physical processes that can lead to observed distributions of element abundances in upper atmospheres of stars of different spectral types. Besides, we give a brief description of some regularities of element abundance distributions in a variety of solar-type stars (in particular, the relation “FIP-effect - spectral type” (FBST)).