THE {sup 12}C + {sup 12}C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/762/1/31· OSTI ID:22167307

Pignatari, M. ^[1]; Hirschi, R.; Bennett, M. ^[2]; Wiescher, M.; Beard, M. ^[3]; Gallino, R. ^[4]; Fryer, C.; Rockefeller, G. ^[5]; Herwig, F.

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1. Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)
2. Astrophysics Group, EPSAM Institute, Keele University, Keele, ST5 5BG (United Kingdom)
3. Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)
4. Universita' di Torino, Torino, Via Pietro Giuria 1, I-10126 Torino (Italy)
5. Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM 87545 (United States)

Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels {sup 12}C({sup 12}C, {alpha}){sup 20}Ne, {sup 12}C({sup 12}C, p){sup 23}Na, and {sup 12}C({sup 12}C, n){sup 23}Mg is poorly determined. Additionally, in C-burning conditions a high {sup 12}C+{sup 12}C rate may lead to lower central C-burning temperatures and to {sup 13}C({alpha}, n){sup 16}O emerging as a more dominant neutron source than {sup 22}Ne({alpha}, n){sup 25}Mg, increasing significantly the s-process production. This is due to the chain {sup 12}C(p, {gamma}){sup 13}N followed by {sup 13}N({beta} +){sup 13}C, where the photodisintegration reverse channel {sup 13}N({gamma}, p){sup 12}C is strongly decreasing with increasing temperature. Presented here is the impact of the {sup 12}C+{sup 12}C reaction uncertainties on the s-process and on explosive p-process nucleosynthesis in massive stars, including also fast rotating massive stars at low metallicity. Using various {sup 12}C+{sup 12}C rates, in particular an upper and lower rate limit of {approx}50,000 higher and {approx}20 lower than the standard rate at 5 Multiplication-Sign 10{sup 8} K, five 25 M {sub Sun} stellar models are calculated. The enhanced s-process signature due to {sup 13}C({alpha}, n){sup 16}O activation is considered, taking into account the impact of the uncertainty of all three C-burning reaction branches. Consequently, we show that the p-process abundances have an average production factor increased up to about a factor of eight compared with the standard case, efficiently producing the elusive Mo and Ru proton-rich isotopes. We also show that an s-process being driven by {sup 13}C({alpha}, n){sup 16}O is a secondary process, even though the abundance of {sup 13}C does not depend on the initial metal content. Finally, implications for the Sr-peak elements inventory in the solar system and at low metallicity are discussed.

• OSTI ID: 22167307
• Journal Information: Astrophysical Journal, Vol. 762, Issue 1; 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
ASTROPHYSICS
CARBON 12 REACTIONS
CARBON 12 TARGET
CARBON 13
CARBON BURNING
COMPARATIVE EVALUATIONS
ELEMENT ABUNDANCE
GIANT STARS
MAGNESIUM 23
MAGNESIUM 25
NEON 20
NEON 22
NITROGEN 13
NUCLEAR REACTION KINETICS
NUCLEOSYNTHESIS
OXYGEN 16
PHOTONUCLEAR REACTIONS
S PROCESS
SODIUM 23
SOLAR SYSTEM