Reaction rates for O-18(alpha, gamma)Ne-22, Ne-22(alpha, gamma)Mg-26, and Ne-22(alpha, n)Mg-25 in stellar helium burning and s-process nucleosynthesis in massive stars

Kaeppeler, F.; Wiescher, M.; Giesen, U.; Göerres, Joachim; Baraffe, I.; Eid, M. El; Raiteri, C. M.; Busso, M.; Gallino, R.; Limongi, Marco; Chieffi, A.

doi:10.1086/175004

Cited by 139 publications

(130 citation statements)

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“…In that work the differences were much larger than what we obtained here. The production factors of 80 Kr in the work by Kaeppeler et al (1994) show a spread between factors of 3 (for the 30 M models) and 25 (for the 15 M models). In our models, the 80 Kr production factors agree within a factor of 2 for a given initial stellar mass (Table 6).…”

Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 86%

“…A comparison of the weak s-process distribution at the end of the He core was already provided by Kaeppeler et al (1994), where the results from the codes FRANEC and Göttingen were discussed for massive stars with a range of initial masses. In that work the differences were much larger than what we obtained here.…”

Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 99%

“…8 for the elemental production factors in the helium core. Part of the reason for the spread found by Kaeppeler et al (1994) is that while the codes were using the same 22 Ne + α rates, different nucleosynthesis networks were used for the simulations. Here we obtain a better consistency (within 25 % for the s-process region) for models with a similar range of stellar masses, giving a brighter view from the comparison.…”

Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 99%

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Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: evolution to the end of core helium burning

Jones¹,

Hirschi²,

Pignatari³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Massive stars are key sources of radiative, kinetic, and chemical feedback in the universe. Grids of massive star models computed by different groups each using their own codes, input physics choices and numerical approximations, however, lead to inconsistent results for the same stars. We use three of these 1D codes-GENEC, KEPLER and MESA-to compute non-rotating stellar models of 15 M , 20 M , and 25 M and compare their nucleosynthesis. We follow the evolution from the main sequence until the end of core helium burning. The GENEC and KEPLER models hold physics assumptions used in large grids of published models. The MESA code was set up to use convective core overshooting such that the CO core masses are consistent with those obtained by GENEC. For all models, full nucleosynthesis is computed using the NuGrid post-processing tool MPPNP.We find that the surface abundances predicted by the models are in reasonable agreement. In the helium core, the standard deviation of the elemental overproduction factors for Fe to Mo is less than 30 %-smaller than the impact of the present nuclear physics uncertainties. For our three initial masses, the three stellar evolution codes yield consistent results. Differences in key properties of the models, e.g., helium and CO core masses and the time spent as a red supergiant, are traced back to the treatment of convection and, to a lesser extent, mass loss. The mixing processes in stars remain the key uncertainty in stellar modelling. Better constrained prescriptions are thus necessary to improve the predictive power of stellar evolution models.

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Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 86%

Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 99%

Section: Nucleosynthesis Up To the End Of Corementioning

confidence: 99%

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Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: evolution to the end of core helium burning

Jones¹,

Hirschi²,

Pignatari³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…However, these extrapolations are not always free from problems. In some cases, they can even lead to wrong results because they don't take into account the contributions of a possible unseen low energy resonances such in 22 Ne(α,n) 25 Mg [3] reaction or a possible sub-threshold resonances like in 13 C(α,n) 16 O [4] and 12 C(α,γ) 16 O [5] reactions. The effect of these resonances may change the extrapolated S-factor at stellar energies by a huge factor, it can be even order of magnitudes.…”

Section: Introductionmentioning

confidence: 99%

Transfer reactions as a tool for nuclear astrophysics

Hammache¹

2013

Proceedings of VI European Summer School on Experimental Nuclear Astrophysics — PoS(ENAS 6)

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The cross section of the nuclear reactions involved in stellar nucleosynthesis are often very difficult to measure directly at stellar energies because of their very low value and/or the radiaoctive nature of the concerned isotopes, often far from the valley of stability. Moreover, this situation can be complicated by the existence of very low energy resonances and/or subthreshold resonances. Indirect methods such as transfer reactions and the ANC method offer the possibility to overcome these difficulties. In this context, the transfer reaction method will be presented and then illustrated through the study of two cases, a resonant reaction case, 12 C(α,γ) 16 O and a direct (n,γ) capture case, 60 Fe(n,γ) 61 Fe

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“…The 22 Ne abundance changes linearly with the initial metallicity of the star (secondary¦ like isotope) because it is produced by α ¦ capture starting from the 14 N, which was built by the initial CNO during the previous H¦ burning. 14 N is converted into 18 O via the 14 N(α,γ) 18 F(β § ) 18 O chain at the beginning of core He¦ burning. When the 4 He abundance is decreased to¨0.1, the temperature in the core starts to increase and, if it gets higher than 2.5© 10 8 K, 18 O is converted into 22 Ne via 18 O(α,γ) 22 Ne.…”

Section: Introductionmentioning

confidence: 99%

The s-process in massive stars: the Shell C-burning contribution

Pignatari¹,

Gallino²,

Baldovin³

et al. 2010

Proceedings of International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX — PoS(NIC-IX)

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In massive stars the s¡ process (slow neutron capture process) is activated at different temperatures, during He¡ burning and during convective shell C¡ burning. At solar metallicity, the neutron capture process in the convective C¡ shell adds a substantial contribution to the s¡ process yields made by the previous core He¡ burning, and the final results carry the signature of both processes. With decreasing metallicity, the contribution of the C¡ burning shell to the weak s¡ process rapidly decreases, because of the effect of the primary neutron poisons. On the other hand, also the s¡ process efficiency in the He core decreases with metallicity.

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Reaction rates for O-18(alpha, gamma)Ne-22, Ne-22(alpha, gamma)Mg-26, and Ne-22(alpha, n)Mg-25 in stellar helium burning and s-process nucleosynthesis in massive stars

Cited by 139 publications

References 0 publications

Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: evolution to the end of core helium burning

Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: evolution to the end of core helium burning

Transfer reactions as a tool for nuclear astrophysics

The s-process in massive stars: the Shell C-burning contribution

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