DYNAMICS OF DUST GRAINS IN THE SHELLS OF AE-HERBIG STARS

The electrostatic charge and dynamics of dust grains in the shell of WW Vulpeculae - a typical Ae Herbig star with Algol-type minima are studied. The important role of the magnetic field in the preservation of charged grains in the inner part of the circumstellar shell is noted. Because the small grains (with radii a < 0,03 mum) are uncharged, they are very quickly swept out of the shell by stellar radiation pressure. As a result of the particles fragmentation during their collisions, a steep size distribution of dust grains may be formed in the shell. Therefore, the parameters of circumstellar and interstellar dust grains must differ greatly.