High-temperature condensates found in meteorites display uranium isotopic variations (235U/238U) that complicate dating the solar system's formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide 247Cm (t1/2 = 15.6 My) into 235U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of 235U reaching ∼+6% relative to average solar system composition, which can only be due to the decay of 247Cm. This allows us to constrain the 247Cm/235U ratio at solar system formation to (7.0 ± 1.6) × 10-5. This value provides new clues on the universality of the nucleosynthetic r-process of rapid neutron capture.
Details
Title
Origin of uranium isotope variations in early solar nebula condensates
Author
Tissot, François L.H. : University of Chicago Dauphas, Nicolas : University of Chicago Grossman, Lawrence : University of Chicago
Data availability statement
All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data are available from the authors upon request. This is Origins Lab contribution number 91.
Funding Information
National Aeronautics and Space Administration, NNX14AK09G National Aeronautics and Space Administration, OJ-30381-0036A National Aeronautics and Space Administration, NNX15AJ25G National Science Foundation, EAR144495 National Science Foundation, EAR150259 National Aeronautics and Space Administration, NNX13AE73G
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