CMS Researchers Push Back the Age of the Solar System

A new study from the Center for Meteorite Studies shifts the birthday of the Solar System up to 2 million years earlier than previously believed. Faculty Research Associate Audrey Bouvier and CMS Director Meenakshi Wadhwa studied calcium-aluminum-rich inclusions (CAIs) in Northwest Africa (NWA) 2364, a relatively recently-discovered CV3 carbonaceous chondrite. Using the 207Pb-206Pb isotope system, they determined that CAIs in NWA 2364 formed 4568.2 million years ago, the oldest age measured thusfar for a Solar System object by 207Pb-206Pb dating. Because CAIs are the earliest formed solids preserved in meteorites, the new age for the NWA 2364 CAIs means that the formation of the proto-Sun and its accompanying nebular disc, from which the planets formed, occurred 0.3-2 million years earlier than previously thought. The ancient age obtained with Pb isotopes was corroborated by dating the CAIs with the 26Al-26Mg system, a short-lived radioisotope system independent of the Pb-Pb system. These results, obtained in the Isotope Cosmochemistry and Geochronology Laboratory in the the ASU School of Earth and Space Exploration, have implications for the input and influence of supernovae on the formation and development of the Solar System. The comprehensive dating work demonstrates the ability of cosmochemists to look back through billions of years of history to the formation of the Solar System and delineate the timing of events with sub-million year resolution. The online version of Bouvier and Wadhwa's paper is available on the Nature Geoscience website.