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Helium-Shell Nucleosynthesis and Extinct RadioactivitiesAlthough the exact site for the origin of the r-process isotopes remains mysterious, most thinking has centered on matter ejected from the cores of massive stars in core-collapse supernovae [13]. In the 1970's and 1980's, however, difficulties in understanding the yields from such models led workers to consider the possibility of r-process nucleosynthesis farther out in the exploding star, in particular, in the helium burning shell [4,5]. The essential idea was that shock passage through this shell would heat and compress this material to the point that the reactions 13C(alpha; n)16O and, especially, 22Ne(alpha; n)25Mg would generate enough neutrons to capture on preexisting seed nuclei and drive an "n process" [6], which could reproduce the r-process abundances. Subsequent work showed that the required 13C and 22Ne abundances were too large compared to the amounts available in realistic models [7] and recent thinking has returned to supernova core material or matter ejected from neutron star-neutron star collisions as the more likely r-process sites.
Document ID
20040065811
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Meyer, B. S.
(Clemson Univ. SC, United States)
The, L.-S.
(Clemson Univ. SC, United States)
Clayton, D. D.
(Clemson Univ. SC, United States)
ElEid, M. F.
(American Univ. Beirut, Lebanon)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Lunar and Planetary Science XXXV: Early Solar System Chronology
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NSF AST-98-19877
Distribution Limits
Public
Copyright
Public Use Permitted.
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