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

Journal Article · Sat May 10 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/786/2/138· OSTI ID:22356948

Hidaka, Hiroshi ^[1]; Yoneda, Shigekazu ^[2]

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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)

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.

• OSTI ID: 22356948
• Journal Information: Astrophysical Journal, Vol. 786, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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