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New FarUltraviolet Intrinsic Spectral Fluxes of Hot Stars and their Photospheric Temperatures Richard. H. Buss Jr., J. W. Kruk
 

Summary: New Far­Ultraviolet 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
H. C. Ferguson 1
Space Telscope Science Institute, 3400 San Martin Dr., Baltimore, Maryland 21218
ABSTRACT
We present photometric, far­ultraviolet (FUV) intrinsic spectra of Galactic OB stars that were acquired by
the orbital Hopkins Ultraviolet Telescope (HUT) at 2--3 š A resolution from – =912--1840 š A. Flux calibrated by
observations of standard white­dwarfs 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 – ? 1000 š A. The best fit T eff are within 500--1000 K of T eff recently derived by others
with longer wavelength (– ? 1200 š A) data (eg. Gulati et al. 1989). The HUT B star fluxes near 1000 š A are
¸ 5% 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
1. Introduction
Thermal radiation from hot OB stars peaks in the far ultraviolet (FUV) for temperatures T ' 10; 000--30,000 K.
These stars thus inject the bulk of their radiant energy into the Galactic Medium at FUV wavelengths where dust absorbs
most strongly (Buss et al. 1994). In this manner, hot stars profoundly influence their surroundings, so the FUV absolute

  

Source: Henry, Richard C.- Department of Physics and Astronomy, Johns Hopkins University

 

Collections: Physics