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Can lightning produce significant levels of mass‐independent oxygen isotopic fractionation in nebular dust?
Author(s) -
Nuth Joseph A.,
Paquette John A.,
Farquhar Adam
Publication year - 2012
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/maps.12037
Subject(s) - formation and evolution of the solar system , nebula , interplanetary dust cloud , isotopes of oxygen , chondrite , presolar grains , meteorite , accretion (finance) , astrobiology , cosmic dust , lightning (connector) , oxygen , fractionation , astrophysics , physics , solar system , chemistry , stars , power (physics) , organic chemistry , quantum mechanics , nuclear physics
Based on recent evidence that oxide grains condensed from a plasma will contain oxygen that is mass‐independently fractionated compared to the initial composition of the vapor, we present a first attempt to evaluate the potential magnitude of this effect on dust in the primitive solar nebula. This assessment relies on previous studies of nebular lightning to provide reasonable ranges of physical parameters to form a very simple model to evaluate the plausibility that lightning could affect a significant fraction of nebular dust and that such effects could cause a significant change in the oxygen isotopic composition of solids in the solar nebula over time. If only a small fraction of the accretion energy is dissipated as lightning over the volume of the inner solar nebula, then a large fraction of nebular dust will be exposed to lightning. If the temperature of such bolts is a few percent of the temperatures measured in terrestrial discharges, then dust will vaporize and recondense in an ionized environment. Finally, if only a small average decrease is assumed in the 16 O content of freshly condensed dust, then over the last 5 Myr of nebular accretion the average Δ 17 O of the dust could increase by more than 30 per mil. We conclude that it is possible that the measured “slope 1” oxygen isotope line measured in meteorites and their components represents a time‐evolution sequence of nebular dust over the last several million years of nebular evolution where 16 O‐rich materials formed first, then escaped further processing as the average isotopic composition of the dust gradually became increasingly depleted in 16 O.