Timescales of Solar System Formation Based on Al–Ti Isotope Correlation by Supernova Ejecta

Abstract

The radioactive decay of short-lived 26Al–26Mg has been used to estimate the timescales over which 26Al was produced in a nearby star and the protosolar disk evolved. The chronology commonly assumes that 26Al was uniformly distributed in the protosolar disk; however, this assumption is challenged by the discordance between the timescales defined by the Al–Mg and assumption-free Pb–Pb chronometers. We find that the 26Al heterogeneity is correlated with the nucleosynthetic stable Ti isotope variation, which can be ascribed to the nonuniform distribution of ejecta from a core-collapse supernova in the disk. We use the Al–Ti isotope correlation to calibrate variable 26Al abundances in Al–Mg dating of early solar system processes. The calibrated Al–Mg chronometer indicates a ≥1 Myr gap between parent body accretion ages of carbonaceous and noncarbonaceous chondrites. We further use the Al–Ti isotope correlation to constrain the timing and location of the supernova explosion, indicating that the explosion occurred at 20–30 pc from the protosolar cloud, 0.94 +0.25/–0.21 Myr before the formation of the oldest solar system solids. Our results imply that the Sun was born in association with a ∼25 Mʘ star.