Duration of Nucleosynthesis

In a recent Letter on a determination of the age of the elements, Reynolds[1] reported the important discovery of isotopically anomalous xenon in the stony meteorite Richarton. The isotopes which appear to occur in significant excess over atmospheric xenon are Xe128, Xe129, Xe130, and Xe131, with the Xe129 dominant by an order of magnitude. At present it does not appear possible to explain all of these data by any single mechanism. Because of the existence of these four anomalies, it is difficult to conclude that the Xe129 excess is simply the product of I129 decay.