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Published September 15, 1989 | Published
Journal Article Open

The presence of ^(146)Sm in the early solar system and implications for its nucleosynthesis


The presence of the p-process nucleus ^(146)Sm (mean life, r = 149 x 10^6 yr) in the early solar system and its in situ ɑ-decay into ^(142)Nd is demonstrated by the correlation of ^(142)Nd/^(144)Nd with ^(144)Sm/^(144)Nd in two meteorites which have a large range in ^(144)Sm/^(144)Nd in their constituent mineral phases. Clear excesses of ^(142)Nd/^(144)Nd, relative to the solar system value, are present in high Sm/Nd phases and a clear deficit of ^(142)Nd/^(144)Nd is observed in one sample with low Sm/Nd. The inferred abundance of ^(146)Sm/^(144)Sm is 0.008 at the time of the last equilibration of each meteorite at 4.47 AE ago, which yields ^(146)Sm/^(144)Sm ~0.015 at the time of formation of the solar system, 4.56 AE ago. These results confirm the presence of ^(146)Sm and provide a well defined initial abundance for ^(146)Sm. The abundance of ^(146)Sm is compatible with the p-process production rate estimates but not with the production rate for ^(146)Sm based on a photodisintegration model for the production of p-process nuclides.

Additional Information

© 1989 American Astronomical Society. Received 1989 June 2; accepted 1989 July 10. We benefited from discussions with W. A. Fowler and S. E. Woosley and comments on the Letter by D. D. Clayton. We acknowledge the contributions of N. Z. Boctor for the petrographic study of Ibitira. We are indebted to I. D. Hutcheon for his interest and support of this work. Mineral separations have benefited from the experience of L. M. Hedges. A piece of Morristown was generously provided by E. J. Olsen. This work was supported by NASA (NAG 9-43) and by a Texaco Postdoctoral Fellowship awarded to the senior author. This is Division Contribution 4766 (670).

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Published - 1989ApJ___344L__81P.pdf


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