Determination of the Galaxy age by the method of uranium–thorium–plutonium isotopic ratios

Abstract

The dependence of the Galaxy age (Т_G), as determined by the method of uranium–thorium isotopic ratios, on the parameters of the nucleosynthesis model is studied within the theory of galactic nucleosynthesis. It is shown that ТG depends strongly both on the scenario of the production of nuclei in the r-process and those features of neutron-rich nuclei that are used in the respective analysis and on galactic-nucleosynthesis parameters. The effect of a sudden nucleosynthesis spike before the formation of a solar system on the Galaxy age is evaluated. The region of admissible values of the parameters of galacticnucleosynthesis theory is discussed. The method of uranium–thorium isotopic ratios is supplemented with the ²⁴⁴Pu/²³⁸U ratio for yet another cosmochronometer pair, and the Galaxy age is estimated on the basis of the model modified in this way.