University of Hertfordshire

From the same journal

By the same authors

Heavy elements and age determinations

Research output: Contribution to journalLiterature review

  • Friedrich-Karl Thielemann
  • P. Hauser
  • E. Kolbe
  • Gabriel Martinez-Pinedo
  • I. Panov
  • T. Rauscher
  • K.L. Kratz
  • B. Pfeiffer
  • S. Rosswog
  • M. Liebendoerfer
  • A. Mezzacappa
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Original languageEnglish
Number of pages20
Pages (from-to)277-296
JournalSpace Science Reviews
Journal publication dateJan 2002
Publication statusPublished - Jan 2002


The age of the universe, measured from the Big Bang to the present, is at the focus of cosmology. Its determination relies, however, on the use of stellar objects or their products. Stellar explosions, like type Ia supernovae serve as standard(izable) candles to measure the expansion of the universe. Hertzsprung-Russell diagrams of globular clusters can determine the age of such clusters and thus are lower limits of the age of the galaxy and therefore also the universe. Some nuclear isotopes with half-lives comparable to the age of galaxies (and the universe) can serve as clocks (chronometers) for the duration of nucleosynthesis. The isotopes U-238 and Th-232 with half-lives of 4.5x10(9) and 1.4x10(10) yr, decaying via alpha decay chains to Pb isotopes, are well suited to serve this purpose. They are products of the same nucleosynthesis process, the r-process. Therefore, the present paper aims at understanding the necessary environment conditions in the (stellar) production sites, the nuclear physics involved, the observational constraints for r-process nucleosynthesis, the results from nucleocosmochronology, and the remaining challenges and uncertainties which need to be overcome for a full understanding of the nature of the r-process.

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