Chemical evolution of galaxies and abundances in low-mass stars

Audouze, J.

doi:10.1007/bf02714312

Cited by 13 publications

(14 citation statements)

References 18 publications

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“…[1,13]. On the other hand, the ν process from 138 Ba via the weak charge-current reaction 138 Ba(ν, e) 138 La was proposed as the cosmic origin of 138 La, and an attempt was made to explain the underproduction of 138 La [1,[13][14][15]. However, the photon-induced reaction rates remain a crucial parameter for the thermonuclear production of 138 La and 139 La.…”

Section: Introductionmentioning

confidence: 99%

Dipole strength inLa139below the neutron-separation energy

et al. 2010

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The γ -ray strength function is an important input quantity for the determination of the photoreaction rate and the neutron capture rate for astrophysics as well as for nuclear technologies. To test model predictions, the photoabsorption cross section of 139 La up to the neutron-separation energy was measured using bremsstrahlung produced at the electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf with an electron beam of 11.5 MeV kinetic energy. The experimental data were analyzed by applying Monte Carlo simulations of γ -ray cascades to obtain the intensities of the ground-state transitions and their branching ratios. We found a significant enhancement of electric dipole strength in the energy range from 6 to 10 MeV that may be related with a pygmy dipole resonance. The present data are combined with photoneutron cross sections for 139 La and compared with results of calculations on the basis of a quasiparticle-random-phase approximation using an instantaneous-shape sampling.

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Section: Introductionmentioning

confidence: 99%

Dipole strength inLa139below the neutron-separation energy

et al. 2010

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“…In these pioneering work, the p-nuclei are synthesized mainly by photodisintegration reactions from pre-existing nuclei. Nevertheless, the origin of the p-nuclei has been discussed during about 50 years and many nucleosynthesis processes have been proposed [6,7,8,9,10,11,12,13]. In our previous paper [14], we reported two empirical scaling laws in the solar system abundances, which are a piece of evidence that the most probable origin of the 27 p-nuclei is γ-process in SNe.…”

Section: Introductionmentioning

confidence: 93%

Universality of the p process

Hayakawa¹,

Iwamoto²,

Kajino³

et al. 2010

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

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The solar abundances provide a concept of universality that the abundance ratios of the p-nucleus to the s-nucleus with the same atomic number are almost constant with the wide region for materials produced by individual stellar nucleosynthesis episode. We study this universality using γ-process calculations with core-collapse supernova explosions under various conditions. The calculated results show that the γ-process under the various conditions can occur but the ratios are almost constant with the wide region independent of the conditions. The shift of γ-process layers, weak s-process and the β -decay after the γ-process contribute to the manifestation of the universality.

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“…The first scaling suggests that the former reactions are likely to play a more important role than the latter reactions. The charged particle reactions in the rp-process [5,6] and proton-induced reactions by cosmic rays [7] change the proton number of seed nuclei. In the ν-process, the charged current interaction that has a contribution larger than the neutral current interaction also changes the proton number [18,19].…”

Section: Analyzing the Solar Abundances And Discovery Of The First Scmentioning

confidence: 99%

“…Nevertheless, their origin has long been discussed with many possible nuclear reactions, and their astrophysical sites have not been identified uniquely. The proposed nuclear processes are the rapid proton capture reactions in novae and type-I X-ray bursts in neutron stars (rp-process) [5,6], the proton-induced reactions by galactic cosmic rays [7], the photodisintegration reactions in supernova (SN) explosions (γ-process or p-process) [4,8,9,10,11,12], and the neutrino-induced reactions in SN explosions (ν-process) [13,14]. The origin of the p-nuclei is crucial to our understanding of how the Solar System material formed and evolved.…”

Section: Introductionmentioning

confidence: 99%

Evidence for p-process nucleosynthesis recorded at the Solar System abundances

Hayakawa¹,

Iwamoto

Shizuma³

et al. 2006

Eur. Phys. J. A

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Abstract. Analyzing the Solar System abundance, we have found two universal scaling laws concerning the p-and s-nuclei with the same atomic number. They are evidence of the p-nucleus origin that has been discussed for long years. The first scaling is the correlation of the isotope abundances between a p-nucleus and an s-nucleus that is two neutron heavier than the p-nucleus. The abundance ratios of the s-nucleus to the p-nucleus are almost constant in a wide range of atomic numbers. This scaling indicates that the p-nucleus is dominantly produced from the s-nucleus by (γ, n) reactions in huge photon bath in supernova explosions. The second scaling indicates that the isotope abundance ratio between two pnuclei with the same atomic number is almost unity. These two scalings are a new useful method to verify nucleosynthesis models for the p-process. We have calculated these ratios by a p-process nucleosynthesis based on a typical core-collapse supernova explosion model. The results are consistent with the scaling in the solar abundances. In addition, the scalings provide new concepts: a universality of the p-process, a rate meter for the s-process and a new nuclear cosmochronometer.PACS. 26.30.+k Nucleosynthesis in novae, supernovae and other explosive environments -98.80.Ft Origin, formation, and abundances of the elements -91.65.Dt Isotopic composition/chemistry

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Chemical evolution of galaxies and abundances in low-mass stars

Cited by 13 publications

References 18 publications

Dipole strength inLa139below the neutron-separation energy

Dipole strength inLa139below the neutron-separation energy

Universality of the p process

Evidence for p-process nucleosynthesis recorded at the Solar System abundances

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