Nucleosynthesis of Heavy Elements by Neutron Capture.

Seeger, P.A.; Fowler, William A.; Clayton, Donald D.

doi:10.1086/190111

Cited by 440 publications

(273 citation statements)

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“…[4]. This difference is significantly smaller than one would expect by simply scaling the product of σ N s that characterizes the reaction flow in the classical s-process approach [41], thus reflecting the more dynamic situation described by the stellar model.…”

Section: -7mentioning

confidence: 88%

TheZr92(n,γ) reaction and its implications for stellar nucleosynthesis

Tagliente¹,

Milazzo²,

Fujii³

et al. 2010

Phys. Rev. C

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Because the relatively small neutron capture cross sections of the zirconium isotopes are difficult to measure, the results of previous measurements are often not adequate for a number of problems in astrophysics and nuclear 0556-2813/2010/81(5)/055801 (9) 055801-1 ©2010 The American Physical Society G. TAGLIENTE et al.PHYSICAL REVIEW C 81, 055801 (2010) technology. Therefore, the 92 Zr(n,γ ) cross section has been remeasured at the CERN n TOF facility, providing a set of improved parameters for 44 resonances in the neutron energy range up to 40 keV. With this information the cross-section uncertainties in the keV region could be reduced to 5% as required for s-process nucleosynthesis studies and technological applications.

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Section: -7mentioning

confidence: 88%

TheZr92(n,γ) reaction and its implications for stellar nucleosynthesis

Tagliente¹,

Milazzo²,

Fujii³

et al. 2010

Phys. Rev. C

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“…Chemical abundances in the solar system indicate that, while Y, Ba, and La, are dominantly formed through slow neutron-capture process, Eu is dominantly a rapid neutron-capture element. The s-and r-process contribution to the solar system abundances is given for example in studies by Seeger et al (1965), Arlandini et al (1999), Simmerer et al (2004), and Sneden et al (2008). At early times in the Galaxy, heavy elements are expected to be due to an r-process contribution, since there was no time for the main s-process to operate, as first suggested by Truran (1981).…”

Section: Introductionmentioning

confidence: 91%

Heavy elements in old very metal-rich stars

Trevisan

Barbuy

2014

A&A

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Context. We studied a sample of high proper motion, old and metal-rich dwarf stars, selected from the NLTT catalogue. The low pericentric distances and eccentric orbits of these solar neighbourhood stars indicate that they might have originated in the inner parts of the Galaxy. Aims. Chemical tagging can probe the formation history of stellar populations. To identify the origin of a sample of 71 very metal-rich dwarf stars, we derive the abundances of the neutron-capture elements Y, Ba, La, and Eu. Methods. The spectroscopic analysis is based on optical high-resolution échelle spectra obtained with the FEROS spectrograph at the ESO 1.52 m Telescope at La Silla, Chile. The abundances of Y, Ba, La, and Eu were derived through LTE analysis, employing the MARCS model atmospheres.Results. The abundances of Y, Ba, La, and Eu vs. Fe and Mg as the reference elements indicate similarities between our sample of old metal-rich dwarf stars and the thin disk. On the other hand, the abundance ratios using O as the reference element, as well as their kinematics, suggest that our sample is clearly distinct from the thin-disk stars. They could be old inner thin-disk stars, as suggested previously, or bulge stars. In either cases, they would have migrated from the inner parts of the Galaxy to the solar neighbourhood.

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“…In all calculations presented here, we have used relative yields for the actinides and trans-actinides from Seeger et al [277], including the estimates of oddeven effects. A recent calculation of the relative abundances of the actinides and trans-actinides by Lingenfelter et al [278] reports essentially the same values as used here by counting progenitors following [129] and [277].…”

Section: The Actinidesmentioning

confidence: 99%

Short-lived nuclei in the early Solar System: Possible AGB sources

et al. 2006

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The abundances of short-lived radionuclides in the early solar system (ESS) are reviewed, as well as the methodology used in determining them. These results are compared with the inventory estimated for a uniform galactic production model. It is shown that, to within a factor of two, the observed abundances of 238 U, 235 U, 232 Th, 244 Pu, 182 Hf, 146 Sm, and 53 Mn are roughly compatible with long-term galactic nucleosynthesis. 129 I is an exception, with an ESS inventory much lower than expected from uniform production. The isotopes 107 Pd, 60 Fe, 41 Ca, 36 Cl, 26 Al, and 10 Be require late addition to the protosolar nebula. 10 Be is the product of energetic particle irradiation of the solar system as most probably is 36 Cl. Both of these nuclei appear to be present when 26 Al is absent. A late injection by a supernova (SN) cannot be responsible for most of the short-lived nuclei without excessively producing 53 Mn; it can however be the source of 53 Mn itself and possibly of 60 Fe. If a late SN injection is responsible for these two nuclei, then there remains the problem of the origin of 107 Pd and several other isotopes. Emphasis is given to an AGB star as a source of many of the nuclei, including 60 Fe; this possibility is explored with a new generation of stellar models. It is shown that if the dilution factor (i.e. the ratio of the contaminating mass to the solar parental cloud mass) is f 0 ∼ 4×10 −3 , a reasonable representation for many nuclei is obtained; this requires that ( 60 Fe/ 56 Fe) ESS ∼ 10 −7 to 2×10 −6 . The nuclei produced by an AGB source do not include 53 Mn, 10 Be or 36 Cl if it is very abundant. The role of irradiation is discussed with regard to 26 Al, 36 Cl and 41 Ca, and the estimates of bulk solar abundances of these isotopes are commented on. The conflict between various scenarios is emphasized as well as the current absence of an astrophysically plausible global interpretation for all the existing data. Examination of abundances for the actinides indicates that a quiescent interval of ∼ 10 8 years is required for actinide group production. This is needed in order to explain the data on 244 Pu and the new bounds on 247 Cm. Because this quiescent interval is not compatible with the 182 Hf data, a separate type of r-process event is needed for at least the actinides, distinct from the two types that have previously been identified. The apparent coincidence of the 129 I and trans-actinide time scales suggests that the last heavy r contribution was from an r-process that produced very heavy nuclei but without fission recycling so that the yields at Ba and below (including I) were governed by fission.

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Nucleosynthesis of Heavy Elements by Neutron Capture.

Cited by 440 publications

References 0 publications

TheZr92(n,γ) reaction and its implications for stellar nucleosynthesis

TheZr92(n,γ) reaction and its implications for stellar nucleosynthesis

Heavy elements in old very metal-rich stars

Short-lived nuclei in the early Solar System: Possible AGB sources

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