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EUV Radiation from Hot Star Photospheres: Theory Versus Observations

Published online by Cambridge University Press:  12 April 2016

Ivan Hubeny  and
Thierry Lanz
Ivan Hubeny
Affiliation:
Universities Space Research Association, NASA Goddard Space Flight Center, Code 681, Greenbelt, MD 20771, USA
Thierry Lanz
Affiliation:
Universities Space Research Association, NASA Goddard Space Flight Center, Code 681, Greenbelt, MD 20771, USA

Abstract

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The only stars other than white dwarfs whose photospheric extreme ultraviolet radiation has been detected are ϵ and β CMa. It is therefore of considerable theoretical interest to compare the EUVE observations of these two giant B stars to predicted spectra. However, both LTE and non-LTE very sophisticated line blanketed model atmospheres fail to match the observed flux. This failure leaves the stellar photosphere theory, even for seemingly “simple” objects as normal B giants were believed to be, in a rather dubious position. This paper briefly summarizes possible reasons for the failure of existing models to describe the EUVE observations of hot stars. In particular, we discuss the effects of uncertainties in the line blanketing, and the effects of the photosphere-wind interaction.

Type
VII. Photospheres and Winds of Early-Type Stars
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 381 - 388
Copyright
Copyright © Kluwer 1996

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