Connection between nonradial pulsations and stellar winds in massive stars. VI. Variability in H alpha, polarization, and magnetic fields in early-type stars

The early-type stars whose spectra show Balmer emission lines are considered, taking into account the division of these stars into two groups, including the OB supergiants and the Be stars. In the case of the Be stars, recent observations at H-alpha, H-beta, and H-gamma with best S/N approximately 500 and resolution approximately 0.1 A have revealed a previously unsuspected winebottle, or two-tier, structure to the symmetric emission profile in several Be stars. For many Be stars, the circumstellar material has an apparent two-component structure. Attention is given to H-alpha variations in four typical Be stars, linear polarization, and magnetic fields. 23 references