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Title: Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.
Authors:
 [1] ;  [2]
  1. Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan)
  2. Department of Science and Engineering, National Museum of Nature and Science, Tsukuba 305-0005 (Japan)
Publication Date:
OSTI Identifier:
22356948
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BARIUM 130; BARIUM 132; CERIUM 136; CERIUM 138; COSMIC RADIATION; ELEMENT ABUNDANCE; IRRADIATION; ISOTOPE RATIO; METEORITES; METEOROIDS; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; PROTONS; SAMARIUM 144; SOLAR SYSTEM; SOLAR WIND; SPACE; STRONTIUM 84; SUN