New Far-Ultraviolet Intrinsic Spectral Fluxes of Hot Stars and Their Photospheric Temperatures

We present photometric, far-ultraviolet (FUV) intrinsic spectra of Galactic OB stars that were acquired by the orbital Hopkins Ultraviolet Telescope (HUT) at 2-3 A resolution in the range λ = 912-1840 A. Flux-calibrated by observations of standard white dwarfs to 5% systematic uncertainty, and corrected for extinction to ~15% random uncertainty, the lightly dereddened B-star spectra agree with Kurucz-model atmospheric fluxes at most wavelengths λ > 1000 A. The best-fit Teff are within 500-1000 K of Teff-values recently derived by others with longer wavelength (λ > 1200 A) data. The HUT B-star fluxes near 1000 A are systematically ~5% higher than the models—just within the systematic uncertainty but yielding FUV color temperatures that are at least 1000-5000 K hotter than models.