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A New Temperature Determination for Sirius B from IUE: Implications for the Observed Soft X-Ray Fluxes

Published online by Cambridge University Press:  12 April 2016

K. Kidder
Affiliation:
Lunar and Planetary Laboratory, University of Arizona Tucson, Arizona85721
J.B. Holberg
Affiliation:
Lunar and Planetary Laboratory, University of Arizona Tucson, Arizona85721
F. Wesemael
Affiliation:
Département de Physique and Observatoire du Mont MéganticUniversitéde Montréal

Abstract

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We have used IUE archive observations to obtain a new and independent estimate of the effective temperature of Sirius B. In this effort we have modeled the observed Lyman alpha profile of Sirius B as a function of effective temperature and find; Teff = 24,500 ± 500 K. This temperature is in good agreement with a recent result obtained from analysis of EXOSAT soft X-ray spectra of Sirius B. In addition to providing confirmation of the soft X-ray result, this temperature implies that Sirius B is significantly cooler and larger in radius than most previous estimates. The radius, R = 0.090 ± 0.005 R, implied by the lower temperature is well in excess of the radius of fully degenerate star having the mass of Sirius B. This investigation employed a unique set of SWP archive spectra, acquired with Sirius B in the small aperture, which have proved to be free of scattered light contamination from Sirius A.

Type
Research Article
Copyright
Copyright © Springer-Verlag 1989

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