Helium burning;
neutron poison;
s process;
R matrix;
PROCESS NUCLEOSYNTHESIS;
NE-21;
D O I:
10.1063/1.4768509
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
The ratio of the reaction rates of the competing channels O-17(alpha,gamma)Ne-21 and O-17(alpha,n)Ne-20 determines the efficiency of O-16 as a neutron poison in the s process in low metallicity rotating stars. It has a large impact on the element production, either producing elements to the mass range of A=90 in case of a significant poisoning effect or extending the mass range up to the region of A=150 if the gamma channel is of negligible strength. We present an improved study of the reaction O-17(alpha, n)Ne-20, including an independent measurement of the O-17(alpha, n(1))Ne-20 channel. A simultaneous R-Matrix fit to both the n(0) and the n(1) channels has been performed. New reaction rates, including recent data on the O-17(alpha,gamma)Ne-21 reaction, have been calculated and used as input for stellar network calculations and their impact on the s process in rotating massive stars is discussed.
机构:
Univ Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USAUniv Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USA
Schoenemann, Spruce W.
Schauer, Andrew J.
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机构:
Univ Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USAUniv Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USA
Schauer, Andrew J.
Steig, Eric J.
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机构:
Univ Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USA
Univ Washington, Quaternary Res Ctr, Seattle, WA 98195 USAUniv Washington, Dept Earth & Space Sci, Isolab, Seattle, WA 98195 USA
机构:
Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USAUniv Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA
Young, Edward D.
Yeung, Laurence Y.
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机构:
Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USAUniv Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA
Yeung, Laurence Y.
Kohl, Issaku E.
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机构:
Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USAUniv Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA