National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

Zr and Mo isotopic constraints on the origins of unusual types of presolar SiC grains.

DE2001768571

Publication Date	2000
Personal Author	Pellin, M. J.; Davis, A. M.; Calaway, W. F.; Lewis, R. S.; Clayton, R. N.
Page Count	5
Abstract	Although most presolar silicon carbide grains form in asymptotic giant branch red giant stars (the so-called mainstream grains) or supernovae (the X-grains), there are a number of other minor types of grains whose origin is less clear. The dominant mechanisms of heavy element nucleosynthesis, the s-process and r-process, are thought to occur mainly in AGB stars and supernovae, respectively (1), and the isotopic patterns in heavy elements in presolar grains can be used to constrain their origins. We have previously reported that mainstream SiC grains have strong enrichments in the s-process isotopes of Sr, Zr and Mo (2-5) and that X-grains have an unusual Mo isotopic composition that differs from s- and r-process expectations (6,7). We report here the first measurements of Zr and Mo isotopes in several grains of other rare types that were found in the same mount as the mainstream and X-grains reported previously.
Keywords	Silicon carbides Supernovae Zirconium Molybdenum Nucleosynthesis Origin R process Red giant stars S process Stars Isotopes
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Argonne National Lab., IL.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200125
Contract Number	W-31-109-ENG-38

Zr and Mo isotopic constraints on the origins of unusual types of presolar SiC grains.

Zr and Mo isotopic constraints on the origins of unusual types of presolar SiC grains.
DE2001768571

Publication Date	2000
Personal Author	Pellin, M. J.; Davis, A. M.; Calaway, W. F.; Lewis, R. S.; Clayton, R. N.
Page Count	5
Abstract	Although most presolar silicon carbide grains form in asymptotic giant branch red giant stars (the so-called mainstream grains) or supernovae (the X-grains), there are a number of other minor types of grains whose origin is less clear. The dominant mechanisms of heavy element nucleosynthesis, the s-process and r-process, are thought to occur mainly in AGB stars and supernovae, respectively (1), and the isotopic patterns in heavy elements in presolar grains can be used to constrain their origins. We have previously reported that mainstream SiC grains have strong enrichments in the s-process isotopes of Sr, Zr and Mo (2-5) and that X-grains have an unusual Mo isotopic composition that differs from s- and r-process expectations (6,7). We report here the first measurements of Zr and Mo isotopes in several grains of other rare types that were found in the same mount as the mainstream and X-grains reported previously.
Keywords	Silicon carbides Supernovae Zirconium Molybdenum Nucleosynthesis Origin R process Red giant stars S process Stars Isotopes
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Argonne National Lab., IL.; Department of Energy, Washington, DC.
Document Type	Conference Proceedings
NTIS Issue Number	200125
Contract Number	W-31-109-ENG-38