Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17 O

Stardust grains recovered from meteorites provide high-precision snapshots of the isotopic composition of the environment in which they formed. Establishing their stellar sites of ori- gin, however, often proves difficult. Asymptotic giant branch (AGB) stars of initial mass 2greater than 4 solar masses produce substantial amounts of dust during their evolution and are predicted to be the site of origin of a large fraction of meteoritic stardust 1, 2 . Yet, no grains have been found to date whose origin can be attributed to these massive AGB stars, potentially highlighting gaps in our understanding of the lifecycle of stars and dust in the Galaxy. Here we show that using the new, increased rate of the 17 O(p,α) 14 N reaction 3 based on a recent underground experiment, we can account for a population of stardust grains that show the 17 O/ 16 O ratios expected from H burning at temperatures of 60–80 million K char- acteristic of massive AGB stars. This result provides the first direct evidence that these stars contributed to the dust inventory from which the Solar System formed.