Stellar origin of the 182 Hf cosmochronometer and the presolar history of solar system matter

Abstract

Relocating a heavy-metal factory: We can learn about the solar system's past by measuring heavy radioactive isotopes in meteorites—the extraterrestrial equivalent of carbon dating on Earth. Elements heavier than iron are mainly synthesized in supernovae or asymptotic giant branch (AGB) stars. Knowing exactly which element is produced where, is key to dating the solar system. Lugaro et al. found that AGB stars generated more of a nuclide called ¹⁸² Hf than previously thought (see the Perspective by Bizzarro). Its abundance indicates that it was produced about 30 million years before the Sun's formation. Science , this issue p. 650 ; see also p. 620