Influence of nuclear physics inputs and astrophysical conditions on Th/U chronometer

Abstract

The productions of thorium and uranium are key ingredients in $r$-process nucleo-cosmochronology. With the combination of improved nuclear and stellar data, we have made detailed investigations on the $r$-process abundance pattern in the very metal-poor halo stars based on the classical $r$-process approach. It is found that the results are almost independent of specified simulations to observed abundances. The influence from nuclear mass uncertainties on Th/U chronometer can approach 2 Gyr. Moreover, the ages of the metal-poor stars HE 1523-0901, CS 31082-001, and BD +17$^\circ$3248 are determined as $11.8\pm 3.7$, $13.5\pm 2.9$, and $10.9 \pm 2.9$ Gyr, respectively. The results can serve as an independent check for age estimate of the universe.Comment: 20 pages, 5 figures. accepted by Phys. Rev.