Observed effects of gravity darkening in rotating B stars.

Predictions of Hardorp and Scholz (1971) concerning the behavior of He I 4471 and Mg H 4481 in the spectra of rapidly rotating B stars are conrirmed by new observations. In early B stars of a given Balmer discontinuity, the equivalent width of He I 4471 is systematically larger in sharp-lined than in broad-lined stars (when corrections are applied for evolutionary effects). In late B stars, the difference between the projected rotational velocities derived according to Slettebak's (1949) method (i.e. neglecting gravity darkening) from Mg H 4481 on the one hand and from He I 4471 on the other, increases towards later spectral types. Key words: B stars - stellar rotation - He I absorption lines