2000A&A...353..707S

The spectrophotometric variability of the magnetic CP star CU Vir in the spectral region from 1150Å to 7850Å is investigated. This study is based on the archival IUE and published visual spectrophotometric data obtained at different phases of the rotational cycle. The light variations in the wavelength region longer than λ 2000Å are generally in antiphase to the variations in the shorter wavelength region, although the shapes of light curves are different. The existence of the ``null wavelength region" at λ2000Å, where the amplitude of light variations is practically zero over the period of rotation, is confirmed. Moreover, the amplitudes of light variations reach the minimum values in the core of L_α line and in the near infrared region. The comparison of the monochromatic light curves with variations of the Si II features shows that the light variations in the far-UV are influenced by the non-uniformity of the silicon distribution over the stellar surface. The total integrated flux of CU Vir varies with phase by about 6.0%. The correlation between the total integrated flux and the magnetic field variations is discussed.