Titre du document

Nuclear cosmochronology

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Nom du Corpus

AstroConcepts

Auteur(s)
  • William A Fowler 1
  • F Hoyle 1
Affiliation(s)
  • Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California, USA
Résumé

In the studies described in this paper we make quantitative use of the radio-active decays of uranium and thorium in cosmochronology in much the same manner as these decays have been employed in geochronology. The paper is divided into two quite different parts representing different views as to the immediate source of the material that now constitutes the solar system.Model 1. The Autonomous Galaxy. From its origin, the Galaxy has been an autonomous system—no further important additions of material from intergalactic space have taken place at subsequent times. Star formation, stellar evolution, and nucleosynthesis have declined at a steady exponential rate over the whole lifetime of the Galaxy. The duration of nucleosynthesis is found to be independent of this rate over rather wide limits.Model 2. Steady-State Cosmology and Galactic-Intergalactic Exchange of Matter. The abundance of the elements in intergalactic matter has reached a steady state through interchange with galaxies in which stars produce elements beyond hydrogen. As a consequence of this same point of view, the Galaxy acquired significant quantities of intergalactic material at various times. This occurred particularly about one billion years before the sun and solar system were formed. Except at epochs of addition of new gas, stellar activity has declined exponentially, as in Model 1.Consideration of the decay of the radioactive isotopes Th232, U235, U238, according to Model 1, leads to the conclusion that the age of the Galaxy is 15?3+5 × 109 years. Similar considerations according to Model 2 lead to the conclusion that the expansion time scale of the universe (the reciprocal of the Hubble constant H) is 11 ± 6 × 109 years. The error can be reduced to ±2 × 109 years if the present thorium-uranium ratio is chosen to give a Pb208Pb206 age for the solar system concordant with that given by Pb>207Pb206, namely 4.5 × 109 years. Applications to the chronology of the Galaxy can no longer be made in a simple manner but the age found in the Model 1 calculations would seem to be a lower limit.

Langue(s) du document
Anglais
Année de publication
1960
Revue

Annals of Physics

Éditeur
Elsevier
Type de publication
journal
Type de document
research-article
Présence de XML structuré
Non
Version de PDF
1.3
Score de qualité du texte
10
Nom du concept
  • Nucleosynthesis
Catégories Science-Metrix
  • 1 - natural sciences ; 2 - physics & astronomy ; 3 - nuclear & particles physics
Catégories Inist
  • 1 - sciences appliquees, technologies et medecines ; 2 - sciences biologiques et medicales ; 3 - sciences biologiques fondamentales et appliquees. psychologie ; 4 - invertebres
Catégories Scopus
  • 1 - Physical Sciences ; 2 - Physics and Astronomy ; 3 - General Physics and Astronomy
Catégories WoS
  • 1 - science ; 2 - physics, multidisciplinary
Identifiant ISTEX
BF412C087CCEA0ED8620CAD948B2DA23FD157FF6
ark:/67375/6H6-3624PG45-K
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