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E Anders

Publications and source records attributed to E Anders.

26 records · Page 2Linked to original sources
PubMed1980

Chemical composition of Earth, Venus, and Mercury.

Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets.

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PubMed1976

Allende meteorite: Isotopically anomalous xenon is accompanied by normal osmium.

The (184)Os/(190)Os ratio of six Allende meteorite samples was determined by neutron activation analysis. Four chromite concentrates gave a ratio differing from the terrestrial ratio by only -0.1 +/- 0.4%, although they contained highly anomalous xenon enriched by up to 67% in (124)Xe and 93% in (136)Xe. In view of this result and the normal isotopic composition of carbon and oxygen in these fractions, it seems very unlikely that the xenon anomalies were produced in a supernova by the p and r processes. More probably, the xenon anomalies were established in the early solar system, by mass fractionation during trapping of noble gases in solids and by spontaneous fission of a superheavy element.Two other samples, containing osmium from the calcium,aluminum-rich inclusions, also gave an (184)Os/(190)Os ratio within -0.1 +/- 0.5% of the terrestrial value, although these inclusions show well-established anomalies in the light elements oxygen and magnesium, which appear to be due to pre-solar dust grains of distinctive nuclear history. Apparently the stellar source of the anomalous oxygen and magnesium did not synthesize heavier elements.

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PubMed1975

Condensation time of the solar nebula from extinct I in primitive meteorites.

Mineral separates from five carbonaceous chondrites were dated by extinct 16 million year (129)I, in an attempt to establish the condensation time of the solar nebula. Two Fe(3)O(4) or Fe(3)O(4)-FeS samples from the Murchison and Orgueil meteorites are older than any other material dated thus far, and apparently formed within 2 x 10(5) years of each other. The great age, close isochronism, and primitive nature of the samples suggest that the event recorded was the condensation stage of the solar nebula. It provides a suitable zero point for the chronology of the early solar system. The (129)I/(127)I ratio during condensation of the nebula was (1.46 +/- 0.04) x 10(-4). The recrystallized C4 chondrite Karoonda began to retain (129)Xe 1.8 +/- 0.5 million years after the above event. This short cooling time implies rapid aceretion (</=1 million years) and a shallow origin (</=10 km) below the surface of its parent body.

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