On the physical model of dust around Wolf-Rayet stars

The observational infrared spectra of a number of Wolf-Rayet stars of WC8-9 spectral classes are shown to be quite satisfactorily explained by making use of the detailed theoretical model of a dust shell made up of spherical amorphous carbon grains, the dynamics, growth-destruction, thermal and electrical charge balance of which are taken into account. The dust grains acquire mainly positive electrical charge, move with suprathermal drift velocities and may grow up to 100-200 W as a result of implantation of impinging carbon ions. For most of the stars the fraction of condensed carbon does not exceed 1 per cent. While the nature of the grain nucleation remains unknown, the condensation distances and the grain seed production can be estimated by fitting the observational spectra with theoretical ones.