Oxygen Isotopic Heterogeneity in the Solar System: The Molecular Cloud Origin Hypothesis and its Implications for Meteorites and the Planets

摘要: The production of O-depleted H2O ice in molecular cloud cores has been suggested from observational data and numerical models which reveal selective ultra-violet dissociation CO isotopomers by the self-shielding effect CO, dominant O-bearing gas species such star-forming environments. During evolution a proto-planetary disk collapsed parent core, difference infall velocity between dust grains likely causes heterogeneous enrichment H2O-vapor reduced C-bearing vaporized organic matter contained grains, respectively. This possibly produces temporal regional heterogeneity local mean O-isotopic composition C/O ratio within inner where thermo-chemical reprocessing metallic elements actively occurs prior to accretion planetesimals. Diversity redox state observed for meteorites can be interpreted as consequence variable environments solar nebula. interpretation predicts that Sun is O-rich, consistent with O-rich implanted wind extracted lunar soil. O-poor compositions are predicted outer planets their satellites would provide future diagnostic test attempting explain system.