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

Richard. H. Buss Jr., J. W. Kruk
Department of Physics and Astronomy,
Johns Hopkins University
Charles and 34th Streets,
Baltimore, Maryland 21218

and

H. C. Ferguson
Space Telscope Science Institute,
3400 San Martin Dr.,
Baltimore, Maryland 21218

Abstract:

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 Å resolution from 912--1840 Å. Flux calibrated by observations of standard white-dwarfs to 5% systematic uncertainty, and corrected for extinction to % random uncertainty, the lightly de-reddened B star spectra agree with Kurucz model atmospheric fluxes at most wavelengths Å. The best fit are within 500--1000 K of recently derived by others with longer wavelength ( Å) data (eg. Gulati et al.\ 1989). The HUT B star fluxes near 1000 Å are % systematically higher than the models --- just within the systematic uncertainty but yielding FUV color temperatures that are at least 1000--5000 K hotter than models.

Subject headings: Ultraviolet: stars --- stars: fundamental parameters --- stars: atmospheres --- atlases



buss@pha.jhu.edu