Rhenium-osmium dating

The isotope 187Re ( rhenium ) has a half-life of 4.12 · 1010 years. This long half-life that allows nuclide 187Re and 187Os to use as a chronometer for the r-process. This idea originally came from D. E. Clayton. 187Re is produced exclusively in the r-process, while 187Os is produced primarily only in the S- process. One can infer the S -process abundance of 187Os About the neighboring isotope 188Os. The rest of the 187Os must be created by the decay of 187Re. The ratio of the abundances of 187Re and 187Os not the primarily generated is then correlated with the onset of r- process events in our galaxy, and thus also with the age of our galaxy.