Titre du document

Distance to Cygnus X-1

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Nom du Corpus

AstroConcepts

Auteur(s)
  • CHUNG-CHIEH CHENG
  • K. J. H. PHILLIPS
  • A. M. WILSON
Résumé

THERE has been much discussion concerning the X-ray object Cygnus X-1 and its optical counterpart, HDE226868, a highly reddened star of type O9.7 Iab (ref. 1). The O star is a single-lined spectroscopic binary, and various assignments of the minimum mass of the secondary, taken to be the X-ray object, suggest that the latter is a black hole. These conclusions are dependent on the mass of the O star being 2030 M, as would be the case if the star were normal for its luminosity class. But the possibility of heating of the primary by the nearby X-ray object, and the spectroscopic indications of mass loss2, indicate that such an assumption is unsafe. In order to determine the mass of HDE226868, a more complete spectroscopic analysis, in which the effective temperature and surface gravity are deduced, and a determination of luminosity (from the distance to the object) are necessary. The distance to the object is crucial to the problem, because once the effective temperature and gravity of the O star are known, the mass will vary as the square of the distance. An error in the distance by a factor of about two means that the model for the X-ray source need not include a black hole.

Langue(s) du document
Indéterminé
Année de publication
1974
Revue

Nature

Éditeur
Nature
Type de publication
journal
Type de document
other
Présence de XML structuré
Oui
Version de PDF
1.4
Score de qualité du texte
4.493
Nom du concept
  • Bok globules
Catégories Science-Metrix
  • 1 - general ; 2 - general science & technology ; 3 - general science & technology
Catégories Inist
  • 1 - sciences appliquees, technologies et medecines ; 2 - sciences biologiques et medicales ; 3 - sciences biologiques fondamentales et appliquees. psychologie
Catégories Scopus
  • 1 - General ; 2 - Multidisciplinary ; 3 - Multidisciplinary
Catégories WoS
  • 1 - science ; 2 - multidisciplinary sciences
Identifiant ISTEX
D4E5D177A917984626AC6FB178B59FB74B21981C
ark:/67375/GT4-NNP9CQT3-J
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