Publisher’s Note: Asymptotic normalization coefficients for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>14</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">N</mml:mi><mml:mo>+</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>15</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:math>and the astrophysical<mml:math xmlns:mml="http://www.w3.

Mukhamedzhanov, A. M.; Bém, P.; Brown, B. Alex; Burjan, V.; Gagliardi, C. A.; Kroha, V.; Novák, Jan; Nunes, F. M.; Piskoř, Š.; Pirlepesov, F.; Šiméčková, E.; Tribble, R. E.; Vincour, J.

doi:10.1103/physrevc.68.019901

Cited by 53 publications

(149 citation statements)

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“…It is worth noting that a reliable extrapolation of the LUNA data to the solar Gamow peak requires combining low-energy with high-energy data, namely the results of the LENA experiment at TUNL (Runkle et al 2005). Additional information is provided by experiments that used indirect methods, such as the Doppler shift attenuation method (Bertone et al 2001;Schürmann et al 2008), Coulomb excitation (Yamada et al 2004), and asymptotic normalization coefficients (ANC; Mukhamedzhanov et al 2003). It is worth noting that the uncertainty on data at high energy affects the low energy extrapolation.…”

Section: Reaction Rate Uncertaintiesmentioning

confidence: 99%

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Cristallo

Leva

Imbriani

et al. 2014

A&A

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Context. The origin of fluorine is a longstanding problem in nuclear astrophysics. It is widely recognized that asymptotic giant branch (AGB) stars are among the most important contributors to the Galactic fluorine production. Aims. In general, extant nucleosynthesis models overestimate the fluorine production by AGB stars with respect to observations. Although those differences are rather small at solar metallicity, low metallicity AGB stellar models predict fluorine surface abundances up to one order of magnitude larger than the observed ones. Methods. As part of a project devoted to reducing the uncertainties in the nuclear physics that affect the nucleosynthesis in AGB stellar models, we review the relevant nuclear reaction rates involved in the fluorine production or destruction. We perform this analysis on a model with initial mass M = 2 M and Z = 0.001. Results. We found that the major uncertainties are due to the 13 C(α,n) 16 O, the 19 F(α,p) 22 Ne, and the 14 N(p,γ) 15 O reactions. A change in the corresponding reaction rates within the present experimental uncertainties implies surface 19 F variations at the AGB tip lower than 10%, thus much smaller than observational uncertainties. For some α capture reactions, however, cross sections at astrophysically relevant energies are determined on the basis of nuclear models, in which some low-energy resonance parameters are very poorly known. Thus, larger variations in the rates of those processes cannot be excluded. That being so, we explore the effects of the variation in some α capture rates well beyond the current published uncertainties. The largest 19 F variations are obtained by varying the 15 N(α,γ) 19 F and the 19 F(α,p) 22 Ne reactions. Conclusions. The currently estimated uncertainties of the nuclear reaction rates involved in the production and destruction of fluorine produce minor 19 F variations in the ejecta of AGB stars. Analysis of some α capture processes that assume a wider uncertainty range determines 19 F abundances in better agreement with recent spectroscopic fluorine measurements at low metallicity. In the framework of this scenario, the 15 N(α,γ) 19 F and the 19 F(α,p) 22 Ne reactions show the strongest effects on fluorine nucleosynthesis. The presence of poorly known low-energy resonances make such a scenario possible, even if it is unlikely. We plan to measure these resonances directly.

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Section: Reaction Rate Uncertaintiesmentioning

confidence: 99%

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Cristallo

Leva

Imbriani

et al. 2014

A&A

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“…There are a few exceptions concerning the key energy-producing reactions. In GENEC, the rate of Mukhamedzhanov et al (2003) was used for 14 N(p ,γ) 15 O below 0.1 GK and the lower limit NACRE rate was used for temperatures above 0.1 GK. This combined rate is very similar to the more recent LUNA rate (Imbriani et al 2004) at relevant temperatures, which is used in MESA.…”

Section: Nuclear Reaction Network and Reaction Ratesmentioning

confidence: 99%

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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“…The measured squares of the ANCs of the ground and the subthreshold states for the channel spin σ = 3/2 in 15 O are 54 ± 6.0 fm −1 and 24.0 ± 5.0 fm −1 [22], correspondingly. The radiative width for the transition of the subthreshold state to the ground state is determined by the product of the squares of the ANCs of these two bound states.…”

Section: Examplesmentioning

confidence: 94%

“…Because the interference between the internal radiative width amplitude (calculated in the singleparticle model) and the real part of the channel radiative width amplitude in the case under consideration is constructive, the channel radiative width Γ 1/2 γ 3/2 (ch) = 0.36 ± 0.07 eV provides a stronger low limit for the total radiative width then Eq. This transition plays an important role in the radiative capture 14 N + p → 15 O + γ, which is the bottleneck reaction in the CNO cycle [21][22][23]. A subthreshold resonance is a bound state, which is close to the threshold.…”

Section: Examplesmentioning

confidence: 99%

Asymptotic normalization coefficients and radiative widths

Mukhamedzhanov

Pang

2015

Phys. Rev. C

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Asymptotic normalization coefficent (ANC) is important quantity in calculation of the radiative width amplitudes providing limits on the radiative width. Here we present some examples showing connection between the ANC and radiative width. In particular, the radiative width of the E1Phys. A 217, 29 (1973) ] is (1.2 ± 0.2) × 10 −2 eV. Meantime the ANC for the first excited state in 17 F puts a low limit on the radiative width, which is (3.4 ± 0.50) × 10 −2 eV. Such a strong disagreement between the measured radiative width and the low limit imposed by the ANC calls for a new measurement of this radiative widh. Other examples are also considered.

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Publisher’s Note: Asymptotic normalization coefficients for14N+p15Oand the astrophysical
A. M. Mukhamedzhanov¹,
P. Bém²,
B. Alex Brown³
et al.

Cited by 53 publications

References 0 publications

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

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

Asymptotic normalization coefficients and radiative widths

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Publisher’s Note: Asymptotic normalization coefficients for14N+p15Oand the astrophysicalA. M. Mukhamedzhanov1, P. Bém2, B. Alex Brown3 et al.

Cited by 53 publications

References 0 publications

Effects of nuclear cross sections on19F nucleosynthesis at low metallicities

Effects of nuclear cross sections on19F nucleosynthesis at low metallicities

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

Asymptotic normalization coefficients and radiative widths

Contact Info

Product

Resources

About

Publisher’s Note: Asymptotic normalization coefficients for14N+p15Oand the astrophysical
A. M. Mukhamedzhanov¹,
P. Bém²,
B. Alex Brown³
et al.

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities