Calcium isotopic anomalies in the Allende meteorite
We report isotopic anomalies in Ca which were found in two Ca-Al-rich inclusions of the Allende meteorite. These inclusions previously had been shown to contain special anomalies for Mg and O which were attributed to fractionation and unknown nuclear effects. The Ca data, when corrected for mass fractionation by using /sup 40/Ca//sup 44/Ca as a standard, show nonlinear isotopic effects in /sup 48/Ca of +13.5 per mil and in /sup 42/Ca of +1.7 per mil for one sample. The second sample shows a /sup 48/Ca depletion of -2.9 per mil, but all other isotopes are normal. Samples with large excesses in /sup 26/Mg show no Ca anomalies. The effects demonstrate that isotopic anomalies exist for higher-atomic-number refractory elements in solar-system materials and do not appear to be readily explainable by a simple model. The correlation of O, Mg, and Ca results on the same inclusions requires the addition and preservation in the solar system of components from idverse nucleosynthetic sources. Observed anomalous Mg and Ca compositions for coexisting mineral phases are uniform within each inclusion, and require initial isotopic homogeneity within an inclusion but the preservation of wide variations between inclusions. Assuming formation of these inclusions by condensation from a gaseous part of the solar nebula, this implies isotopic heterogeneity on a scale of 10-10/sup 2/ km within the nebula.
- Research Organization:
- The Lunatic Asylum, Division of Geological and Planetary Sciences, California Institute of Technology
- OSTI ID:
- 5078835
- Journal Information:
- Astrophys. J., Lett.; (United States), Vol. 220:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
CALCIUM ISOTOPES
ISOTOPE RATIO
NUCLEOSYNTHESIS
METEORITES
CHEMICAL COMPOSITION
ABUNDANCE
FRACTIONATION
SOLAR NEBULA
SUPERNOVAE
ALKALINE EARTH ISOTOPES
ISOTOPES
NEBULAE
SEPARATION PROCESSES
STARS
640101* - Astrophysics & Cosmology- Cosmic Radiation