¹Kvasnytsya, V.M.
Journal of Superhard Materials 40, 229-235 Link to Article [DOI: 10.3103/S1063457618040019]
¹Semenenko Institute of Geochemistry, Mineralogy and Ore Formation, National Academy of Sciences of Ukraine, pr. Palladina 34, Kiev 142, 03680, Ukraine

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¹Alqudah, M.,²Khoury, H., ²Salameh, E., ³Mutterlose, J.
Arabian Journal of Geosciences 11, 451 Link to Article [DOI: 10.1007/s12517-018-3776-z]
¹Department of Earth and Environmental Sciences, Yarmouk University, 21163, Irbid, Jordan
²Department of Geology, University of Jordan, Amman, 11942, Jordan
³Institute for Geology, Mineralogy and Geophysics, Ruhr University Bochum, Universitätsstraße 150, Bochum, 44801, Germany

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¹Hsiang-Wen Hsu et al. (>10)
Science 362, eaat3185 Link to Article [DOI: 10.1126/science.aat3185]
1Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, Boulder, CO, USA
Reprinted with permission from AAAS

Saturn’s main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft’s traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We report the direct in situ detection of material from Saturn’s dense rings by the CDA impact mass spectrometer. Most detected grains are a few tens of nanometers in size and dynamically associated with the previously inferred “ring rain.” Silicate and water-ice grains were identified, in proportions that vary with latitude. Silicate grains constitute up to 30% of infalling grains, a higher percentage than the bulk silicate content of the rings.

¹Thomas Kenkmann, ²Kent A. Sundell, ³Douglas Cook
Scientific Reports 8, 13246 Link to Article [https://doi.org/10.1038/s41598-018-31655-4]
¹Institut für Geo- und Umweltnaturwissenschaften, Albert-Ludwigs-Universität Freiburg, Baden-Württemberg, Germany
²Casper College, Casper, WY, USA
³Independent Consultant, Colorado Springs, CO, USA

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Mario Fischer-Gödde^1,2, Daniel Schwander³, and Ulrich Ott^4,5
The Astronomical Journal 156, 176 Link to Article [https://doi.org/10.3847/1538-3881/aadf33]
¹Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, D-50674 Köln, Germany
²Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany
³Steinmann-Institut, Rheinische Friedrich-Wilhelms-Universität, Meckenheimer Allee 169, D-53115 Bonn, Germany
⁴MTA Atomki, Bem tér 18/c, HU-4026 Debrecen, Hungary
⁵Max-Planck-Institut für Chemie, Hahn-Meitner-Weg 1, D-55128 Mainz, Germany

Refractory metal nuggets (RMNs) are among the first solids formed in the nascent solar system. They contain high abundances of refractory metals like Re, Os, W, Ir, Ru, and Pt. The isotopic compositions of these elements bear testimony to the stellar sources that contributed to the nucleosynthetic makeup of our solar system. We report the first high-precision Ru isotope data for a bulk RMN sample prepared from the Allende meteorite. The RMNs display well-resolved mass-independent anomalies with positive anomalies for ⁹⁶Ru, ⁹⁸Ru, ¹⁰⁰Ru, ¹⁰²Ru, and ¹⁰⁴Ru. These are best explained by a deficit in r-process combined with a slight deficit in p-process nuclides. This finding stands in stark contrast to the s-process deficit isotopic patterns observed for Allende Ca–Al-rich inclusions (CAIs), bulk Allende, and other bulk meteorites. The contrasting r-, p-deficit versus s-deficit Ru isotopic signatures observed between RMNs and CAIs is surprising, given that CAIs are assumed to be a major host phase of RMNs. One way to explain the s-deficit patterns observed for CAIs and bulk meteorites is that r– and p-process Ru nuclides were added to the solar nebula after RMN formation and prior to the formation of CAIs and the accretion of meteorite parent bodies. A possible source may have been a nearby core-collapse supernova that injected freshly synthesized r– and p-process nuclides into the nascent solar system. The injection of such r– and p-enriched matter represents an alternative mechanism to account for the s-process variability presented by CAIs and bulk carbonaceous meteorites.