An investigation of the micro-variations of highly luminous OBA type stars. V.

The optical microvariations of eight high luminous stars, five of type O, two of type B, and one of type A are analyzed. The reddening, temperatures, gravities, and characteristic periods for the stars are estimated. The changes in the light and color curves are discussed. The amplitude-wavelength relation is studied. It is observed that seven of the stars are variable and characteristic periods for only three of the stars are detected in the light curve. The data reveal that the amplitudes of light variations are largest in the ultraviolet for BA type supergiants; for some O type stars there is little difference between the amplitudes at short and long wavelengths.