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Title: Barium isotopes in individual presolar silicon carbide grains from the Murchison meteorite.

Barium isotopic compositions of single 2.3-5.3 {mu}m presolar SiC grains from the Murchison meteorite were measured by resonant ionization mass spectrometry. Mainstream SiC grains are enriched in s-process barium and show a spread in isotopic composition from solar to dominantly s-process. In the relatively coarse grain size fraction analyzed, there are large grain-to-grain variations of barium isotopic composition. Comparison of single grain data with models of nucleosynthesis in asymptotic giant branch (AGB) stars indicates that the grains most likely come from low mass carbon-rich AGB stars (1.5 to 3 solar masses) of about solar metallicity and with approximately solar initial proportions of r- and s-process isotopes. Measurements of single grains imply a wide variety of neutron-to-seed ratios, in agreement with previous measurements of strontium, zirconium and molybdenum isotopic compositions of single presolar SiC grains.
Authors:
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Publication Date:
OSTI Identifier:
949642
Report Number(s):
ANL/MSD/JA-42786
Journal ID: ISSN 0016-7037; GCACAK; TRN: US201012%%425
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geochim. Cosmochim. Acta; Journal Volume: 67; Journal Issue: 17 ; Sep. 2003
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Aeronautic and Space Administration (NASA); FOR
Country of Publication:
United States
Language:
ENGLISH
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BARIUM; BARIUM ISOTOPES; GRAIN SIZE; IONIZATION; MASS SPECTROSCOPY; METEORITES; MOLYBDENUM; NUCLEOSYNTHESIS; S PROCESS; SILICON CARBIDES; STARS; STRONTIUM; ZIRCONIUM