This is represented by a solid curve in Fig. The explanation of this dependence is the same as in the previous section. Thirdly, on average, Be stars of earlier spectral type exhibit larger values of polarization. The distributions of for different spectral subgroups of Be stars will be considered later in Sect. 2 c the values of are plotted against spectral type for the entire sample.
First impressions suggest that there are no significant differences in for the subtypes of Be stars.
However, there is a possible trend in the average values in the sense that later spectral type stars rotate faster than early ones. The value of projected rotational velocity shows a large scatter for all Be star subspectral types but with a clear concentration around the values between 200 to 250 kms -1 . All Be stars exhibit a projected rotational velocities which are less than a critical rotational velocity for the given spectral type. We will investigate the distribution of in more detail in the next section.