Co-Production of Light p-, s- and r-Process Isotopes in the High-Entropy Wind of Type II Supernovae

Farouqi, K.; Kratz, K. L.; Pfeiffer, B.

doi:10.1071/as08075

Cited by 40 publications

(42 citation statements)

References 44 publications

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“…From about Nb on, our model predicts a smooth transition into a true rapid neutron-capture r-process. This seems, indeed, to be confirmed by recent astrophysical and cosmochemical observations (see, e.g., Kratz et al 2008;Farouqi et al 2009aFarouqi et al , 2009b. Therefore, in this mass region the classical definition of the so-called solar system r-process "residuals" defined as N − N s, = N r, should no longer be applied.…”

Section: Discussionmentioning

confidence: 85%

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

Farouqi¹,

Kratz²,

Pfeiffer³

et al. 2010

ApJ

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209

293

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The astrophysical site of the r-process is still uncertain, and a full exploration of the systematics of this process in terms of its dependence on nuclear properties from stability to the neutron drip-line within realistic stellar environments has still to be undertaken. Sufficiently high neutron-to-seed ratios can only be obtained either in very neutron-rich low-entropy environments or moderately neutron-rich high-entropy environments, related to neutron star mergers (or jets of neutron star matter) and the high-entropy wind of core-collapse supernova explosions. As chemical evolution models seem to disfavor neutron star mergers, we focus here on high-entropy environments characterized by entropy S, electron abundance Y e , and expansion velocity V exp . We investigate the termination point of charged-particle reactions, and we define a maximum entropy S final for a given V exp and Y e , beyond which the seed production of heavy elements fails due to the very small matter density. We then investigate whether an r-process subsequent to the charged-particle freeze-out can in principle be understood on the basis of the classical approach, which assumes a chemical equilibrium between neutron captures and photodisintegrations, possibly followed by a β-flow equilibrium. In particular, we illustrate how long such a chemical equilibrium approximation holds, how the freeze-out from such conditions affects the abundance pattern, and which role the late capture of neutrons originating from β-delayed neutron emission can play. Furthermore, we analyze the impact of nuclear properties from different theoretical mass models on the final abundances after these late freeze-out phases and β-decays back to stability. As only a superposition of astrophysical conditions can provide a good fit to the solar r-abundances, the question remains how such superpositions are attained, resulting in the apparently robust r-process pattern observed in low metallicity stars.

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Section: Discussionmentioning

confidence: 85%

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

Farouqi¹,

Kratz²,

Pfeiffer³

et al. 2010

ApJ

Self Cite

209

293

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“…This is the so-called n-process (Blake & Schramm 1976), causing a short neutron burst, which has been proposed by Meyer et al (2000) to be responsible for the Mo isotopic pattern found in X grains (Pellin et al 1999). An alternative model to explain the Mo isotopic pattern in X grains has been proposed by Farouqi et al (2009). In this model the Mo isotopes are produced by charged particles (mostly α particles) in the high-entropy wind of Type II SNe.…”

Section: Type C Grains and Their Stellar Sourcesmentioning

confidence: 99%

SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE

Zinner

Gallino

et al. 2015

ApJ

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We report C, Si, N, S, Mg-Al, and Ca-Ti isotopic compositions of presolar silicon carbide (SiC) grains from the SiC-rich KJE size fraction (0.5-0.8 µm) of the Murchison meteorite. One thousand one hundred thirteen SiC grains were identified based on their C and Si isotopic ratios. Mainstream, AB, C, X, Y, and Z subtypes of SiC, and X-type silicon nitride (Si 3 N 4) account for 81.4%, 5.7%, 0.1%, 1.5%, 5.8%, 4.9%, and 0.4%, respectively. Twenty-five grains with unusual Si isotopic ratios, including one C grain, 16 X grains, 1 Y grain, 5 Z grains, and 2 X-type Si 3 N 4 grains were selected for N, S, Mg-Al, and Ca-Ti isotopic analysis. The C grain is highly enriched in 29 Si and 30 Si (δ 29 Si = 1345‰ ± 19‰, δ 30 Si = 1272‰ ± 19‰). It has a huge 32 S excess, larger than any seen before, and larger than that predicted for the Si/S supernova (SN) zone, providing evidence against the elemental fractionation model by Hoppe et al. Two SN models investigated here present a more satisfying explanation in terms of a radiogenic origin of 32 S from the decay of short-lived 32 Si (τ 1/2 = 153 yr). Silicon-32 as well as 29 Si and 30 Si can be produced in SNe by short neutron bursts; evidence for initial 44 Ti (τ 1/2 = 60 yr) in the C grain is additional evidence for an SN origin. The X grains have marginal 32 S excesses, much smaller than expected from their large 28 Si excesses. Similarly, the Y and Z grains do not show the S-isotopic anomalies expected from their large Si isotopic anomalies. Low intrinsic S contents and contamination with isotopically normal S are the most likely explanations.

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“…Another process in core-collapse supernovae (CCSNe) that can produce the light p-process nuclei up to Pd−Ag, including 92 Nb, is the combination of α, proton, neutron captures, and their reverse reactions in α-rich freezeout conditions (15). Neutrino winds from the forming neutron star are also a possible site for the production of the light p-process nuclei (16)(17)(18), although one of its possible components [the so-called νp-process (19)] cannot produce 92 Nb because it is shielded by 92 Mo (5,20). The same occurs in the case of the rp process in X-ray bursts (21).…”

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confidence: 99%

Origin of the p -process radionuclides ⁹² Nb and ¹⁴⁶ Sm in the early solar system and inferences on the birth of the Sun

Lugaro

Pignatari

Ott

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The abundances of 92 Nb and 146 Sm in the early solar system are determined from meteoritic analysis, and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the explosion of white dwarfs with mass above the Chandrasekhar limit is in agreement with the abundance of 53 Mn, another radionuclide present in the early solar system and produced in the same events. Mo ratio in the early solar system to be at least 50% lower than the current nominal value, which is outside its present error bars. A different solution is to invoke another production site for 92 Nb, which we find in the α-rich freezeout during core-collapse supernovae from massive stars. Whichever scenario we consider, we find that a relatively long time interval of at least ∼10 My must have elapsed from when the star-forming region where the Sun was born was isolated from the interstellar medium and the birth of the Sun. This is in agreement with results obtained from radionuclides heavier than iron produced by neutron captures and lends further support to the idea that the Sun was born in a massive star-forming region together with many thousands of stellar siblings.short-lived radionuclides | solar system formation | supernovae

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Co-Production of Light p-, s- and r-Process Isotopes in the High-Entropy Wind of Type II Supernovae

Cited by 40 publications

References 44 publications

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE

Origin of the p -process radionuclides ⁹² Nb and ¹⁴⁶ Sm in the early solar system and inferences on the birth of the Sun

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Co-Production of Light p-, s- and r-Process Isotopes in the High-Entropy Wind of Type II Supernovae

Cited by 40 publications

References 44 publications

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae

SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE

Origin of the p -process radionuclides 92 Nb and 146 Sm in the early solar system and inferences on the birth of the Sun

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Product

Resources

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Origin of the p -process radionuclides ⁹² Nb and ¹⁴⁶ Sm in the early solar system and inferences on the birth of the Sun