NEW DETERMINATION OF THE {sup 13}C({alpha}, n){sup 16}O REACTION RATE AND ITS INFLUENCE ON THE s-PROCESS NUCLEOSYNTHESIS IN AGB STARS

Journal Article · Mon Sep 10 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/756/2/193· OSTI ID:22092337

Guo, B.; Li, Z. H.; Li, Y. J.; Su, J.; Yan, S. Q.; Bai, X. X.; Chen, Y. S.; Fan, Q. W.; Jin, S. J.; Li, E. T.; Li, Z. C.; Lian, G.; Liu, J. C.; Liu, X.; Shu, N. C. ^[1]; Lugaro, M.; Buntain, J. ^[2]; Pang, D. Y. ^[3]; Karakas, A. I. ^[4]; others, and

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1. China Institute of Atomic Energy, P.O. Box 275(1), Beijing 102413 (China)
2. Monash Centre for Astrophysics, Monash University, Clayton 3800, Victoria (Australia)
3. School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)
4. Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Weston Creek ACT 2611 (Australia)

We present a new measurement of the {alpha}-spectroscopic factor (S{sub {alpha}}) and the asymptotic normalization coefficient for the 6.356 MeV 1/2{sup +} subthreshold state of {sup 17}O through the {sup 13}C({sup 11}B, {sup 7}Li){sup 17}O transfer reaction and we determine the {alpha}-width of this state. This is believed to have a strong effect on the rate of the {sup 13}C({alpha}, n){sup 16}O reaction, the main neutron source for slow neutron captures (the s-process) in asymptotic giant branch (AGB) stars. Based on the new width we derive the astrophysical S-factor and the stellar rate of the {sup 13}C({alpha}, n){sup 16}O reaction. At a temperature of 100 MK, our rate is roughly two times larger than that by Caughlan and Fowler and two times smaller than that recommended by the NACRE compilation. We use the new rate and different rates available in the literature as input in simulations of AGB stars to study their influence on the abundances of selected s-process elements and isotopic ratios. There are no changes in the final results using the different rates for the {sup 13}C({alpha}, n){sup 16}O reaction when the {sup 13}C burns completely in radiative conditions. When the {sup 13}C burns in convective conditions, as in stars of initial mass lower than {approx}2 M{sub Sun} and in post-AGB stars, some changes are to be expected, e.g., of up to 25% for Pb in our models. These variations will have to be carefully analyzed when more accurate stellar mixing models and more precise observational constraints are available.

• OSTI ID: 22092337
• Journal Information: Astrophysical Journal, Vol. 756, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ALPHA REACTIONS
ASTROPHYSICS
ASYMPTOTIC SOLUTIONS
BORON 11 REACTIONS
CAPTURE
CARBON 13 TARGET
CARBON BURNING
ISOTOPE RATIO
LITHIUM 7
MEV RANGE
NUCLEAR REACTION KINETICS
NUCLEOSYNTHESIS
OXYGEN 16
OXYGEN 17
S PROCESS
SPECTROSCOPIC FACTORS
STAR MODELS
STARS
TRANSFER REACTIONS