Rotationally broadened SiII 6347 model line profile in a main sequence B2-type star (rest T_eff = 19   000 K, log g = 4.0) seen at the inclination angle i = 45°. a) Line profiles affected by gravitational darkening in stars rotating at different surface Ω/Ω_c rates and differential rotation parameter α = 0.0; b) Line profiles with gravitational darkening effect in stars rotating at Ω_o/Ω_c = 0.9 and for several values of the differential rotation parameter α. To calculate the line profiles, we used fi_GD = 0.25.