Ultraviolet energy distributions of luminous early-type stars from TD1 satellite observations

Ultraviolet spectra are presented for supergiants, giants, and main-sequence stars in the spectral type range from B0 to A2. The observations were obtained in the spectral range A with the S2/68 Ultraviolet Sky Survey Telescope in the TD1 satellite. The effect of luminosity has been studied by comparing the ultraviolet energy distributions of luminous and main-sequence stars of the same spectral type. The flux deficiencies which are observed in the energy distributions of luminous stars are interpreted as the result of lower effective temperatures for luminous stars than for corresponding main-sequence stars, and an estimate is given of the effective temperature scale for B-type supergiants. Subject headings: early-type stars - spectra, ultraviolet - spectrophotometry