Common properties of some Be stars optical polarization parameters

The long-term changes of the intrinsic polarization percentage are evident in the stars O And, γ Cas, 88 Her (during the period 1974–1992), κ Dra (1979–1992) and BU Tau (1986–1992). The amplitudes of the polarization percentage variations are not more than a half of the percent. The changes of the position angles are within an interval of about 30 degrees.