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Spatial heterogeneity of 26 Al/ 27 Al and stable oxygen isotopes in the solar nebula
Author(s) -
Boss Alan P.
Publication year - 2006
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2006.tb00445.x
Subject(s) - formation and evolution of the solar system , nebula , isotopes of oxygen , chondrule , isotope , presolar grains , oxygen , astrophysics , solar system , meteorite , physics , analytical chemistry (journal) , chondrite , astrobiology , chemistry , nuclear physics , stars , chromatography , quantum mechanics
— The degree of isotopic spatial heterogeneity in the solar nebula has long been a puzzle, with different isotopic systems implying either large‐scale initial spatial homogeneity (e.g., 26 Al chronometry) or a significant amount of preserved heterogeneity (e.g., ratios of the three stable oxygen isotopes, 16 O, 17 O, and 18 O). We show here that in a marginally gravitationally unstable (MGU) solar nebula, the efficiency of large‐scale mixing and transport is sufficient to spatially homogenize an initially highly spatially heterogeneous nebula to dispersions of ˜10% about the mean value of 26 Al/ 27 Al on time scales of thousands of years. A similar dispersion would be expected for 17 O/ 16 O and 18 O/ 16 O ratios produced by ultraviolet photolysis of self‐shielded molecular CO gas at the surface of the outer solar nebula. In addition to preserving a chronological interpretation of initial 26 Al/ 27 Al ratios and the self‐shielding explanation for the oxygen isotope ratios, these solar nebula models offer a self‐consistent environment for achieving large‐scale mixing and transport of thermally annealed dust grains, shock‐wave processing of chondrules and refractory inclusions, and giant planet formation.