Galactic Age Estimates from O-rich Stardust in Meteorites

The ${}^{16}\mathrm{O}{/}^{17}\mathrm{O}$ and ${}^{16}\mathrm{O}{/}^{18}\mathrm{O}$ ratios of refractory oxide grains extracted from primitive meteorites suggest that they originated in low-mass red giant stars prior to the formation of the Solar System $4.6\times {10}^9$ years ago. Detailed comparison of the isotopic compositions of the grains with models of stellar evolution and galactic chemical evolution imply that the age of the Galaxy is 14.4 Gyr with a statistical error of $\pm 1.3\mathrm{Gyr}$. Systematic uncertainties are of order several Gyr, however, and are primarily due to inadequacies in present theoretical modeling.