Uncertainties in the Th cosmochronometry

TL;DR

This paper examines the uncertainties in using thorium (Th) cosmochronometry for estimating the ages of the oldest stars and the Galaxy, highlighting the impact of nuclear, astrophysical, and observational factors.

Contribution

It analyzes how various uncertainties affect Th-based age predictions and discusses potential improvements through more accurate observations of heavy r-elements.

Findings

Uncertainties significantly impact Th cosmochronometry accuracy

Current models require careful interpretation due to nuclear and observational errors

Future observations could improve age estimates by accurately measuring Th and U lines

Abstract

Recent observations of r-nuclei, and in particular of Th, in ultra-metal poor stars revived the old idea that the Th cosmochronometry could provide an age estimate of the oldest stars in the Galaxy, and therefore a lower limit to the age of the Galaxy. Unfortunately, some nuclear, astrophysics and observational uncertainties still affect the theoretical r-process models required to predict the original production of Th. The impact of these uncertainties on the prediction of the age of the Galaxy is analyzed and discussed. Although the present study suggests that at the moment great care should be taken in estimating the age of the stars on the basis of the observed Th abundance, new accurate observations of heavy r-elements could put the Th cosmochronometry on safer grounds, especially if Th and U lines could be observed accurately and simultaneously in metal-poor stars.