Sulfur four isotope NanoSIMS analysis of comet-81P/Wild 2 dust in impact craters on aluminum foil C2037N from NASA’s Stardust mission

Authors

  • Philipp R. HECK,

    Corresponding author
    1. Robert A. Pritzker Center for Meteoritics and Polar Studies, Department of Geology, The Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605, USA
    2. Chicago Center for Cosmochemistry, The University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, USA
    3. Nano- and Microparticle Research Group, Particle Chemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, D-55020 Mainz, Germany
      Corresponding author. E-mail: prheck@fieldmuseum.org
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  • Peter HOPPE,

    1. Nano- and Microparticle Research Group, Particle Chemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, D-55020 Mainz, Germany
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  • Joachim HUTH

    1. Nano- and Microparticle Research Group, Particle Chemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, D-55020 Mainz, Germany
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Corresponding author. E-mail: prheck@fieldmuseum.org

Abstract

Abstract– We present NanoSIMS four-isotope S analyses of 24 comet Wild 2 dust impact residues in craters on aluminum foil C2037N returned by NASA’s Stardust mission. Except for one sample, all impact residues have normal S isotopic compositions within 2σ uncertainties of at least two S isotope ratios. This implies that most S-rich Wild 2 dust impactors formed in the solar system. Instrumental isotope fractionation due to sample topography is the main contribution to our analytical uncertainty. One impact crater residue shows small anomalies of δ33S = −57 ± 17‰, and δ34S = −41 ± 17‰ (1σ uncertainties). Although this could be simply a statistical outlier or the fingerprint of a chemical isotope fractionation it is also possible that the observed anomaly results from the mixture of a cometary FeS particle with a small (150 nm diam.) presolar FeS supernova grain. This would translate into a presolar sulfide abundance of approximately 200 ppm.

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