S-Process BA Isotopic Compositions in Presolar SiC from the Murchison Meteorite
Abstract
We have measured, by thermal ionization mass spectrometry, the isotopic composition of Ba in interstellar SiC-enriched samples (the KJ series) prepared from the Murchison meteorite. Ba in these samples is strongly enriched in components plausibly understood as s-process nucleosynthetic products. Inferred s-process compositions are different from the average s-process contribution to solar system materials in the sense of indicating lower effective neutron exposure. There are variations in s-process compositions which correlate with grain size, indicating lower neutron exposure for the larger grains. The inferred s-process compositions differ significantly from previous theoretical predictions, indicating the need for revision of relevant neutron capture cross sections and providing a target for more detailed modeling of s-process nucleosynthesis in specific stellar environments.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1993
- DOI:
- 10.1086/172756
- Bibcode:
- 1993ApJ...410..393P
- Keywords:
-
- Barium Isotopes;
- Interstellar Matter;
- Murchison Meteorite;
- Nuclear Astrophysics;
- Silicon Carbides;
- Solar System;
- Interstellar Chemistry;
- Mass Spectroscopy;
- Neutron Cross Sections;
- METEORITES;
- STONY METEORITES;
- CHONDRITES;
- MURCHISON;
- ISOTOPES;
- IMS;
- COMPOSITION;
- SILICON CARBIDE;
- MASS SPECTROMETRY;
- SAMPLES;
- METEORITE;
- LABORATORY STUDIES;
- BARIUM;
- ENRICHMENT;
- NUCLEOSYNTHESIS;
- S PROCESS;
- ABUNDANCE;
- PROCEDURE;
- CM2 CHONDRITES;
- THEORETICAL STUDIES;
- MODEL;
- COMPARISON;
- Lunar and Planetary Exploration; Meteorites;
- METEOROIDS;
- NUCLEAR REACTIONS;
- NUCLEOSYNTHESIS;
- ABUNDANCES