The Nature of Light Variations of the He-Strong CP Star HD 37776
  We calculated spectral energy distribution of the helium strong chemically peculiar star HD 37776 using adequate model atmospheres. We show that the chemical peculiarity influences the stellar energy distribution. Consequently, spots of peculiar chemical composition on the surface of a rotating star may cause detectable light variations of the star. However, the observed light variations are not likely caused by an uneven surface distribution of helium, but may be due to spots of metals (mainly carbon). 
Jiri Krticka, Zdenek Mikulasek, Juraj Zverko and Josef Ziznovsky