Alpha clustering and the stellar nucleosynthesis of carbon

Krauss, H.; Grün, K.; Rauscher, T.; Abele, H.; Mohr, P.; Staudt, G.

doi:10.1007/978-3-642-79696-8_17

Cited by 3 publications

(3 citation statements)

References 10 publications

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“…Of course, fine-tuning has long been discussed in nuclear physics, but usually in connection to the position of the Hoyle state of 12 C (see, for example, Ref. [40]). An immediate question is to which extent the latter arises from the fine-tunings we discussed here.…”

Section: Discussionmentioning

confidence: 99%

αα scattering in halo effective field theory

2008

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We study the two-alpha-particle (αα) system in an Effective Field Theory (EFT) for halo-like systems. We propose a power counting that incorporates the subtle interplay of strong and electromagnetic forces leading to a narrow resonance at an energy of about 0.1 MeV. We investigate the EFT expansion in detail, and compare its results with existing low-energy αα phase shifts and previously determined effective-range parameters. Good description of the data is obtained with a surprising amount of fine-tuning. This scenario can be viewed as an expansion around the limit where, when electromagnetic interactions are turned off, the 8 Be ground state is at threshold and exhibits conformal invariance. We also discuss possible extensions to systems with more than two alpha particles.

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Section: Discussionmentioning

confidence: 99%

αα scattering in halo effective field theory

2008

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“…To be sure, there is a second branch in the tabulated reaction rates which is uncertain by a large factor, but this becomes more important than the main branch only for T > 51 10 8 K, being thus irrelevant for the ash conditions.] Oberhummer et al (1994) have recently analyzed the triple-process from a di erent perspective. These authors have shown that even extremely small variations in the strength of the e ective nucleon-nucleon interaction (i.e., by 0:1% 0:2%) may have a large impact upon the reaction rates.…”

Section: Reaction Ratesmentioning

confidence: 99%

The Helium-Core Mass at the Helium Flash in Low-Mass Red Giant Stars: Observations and Theory

Catelan¹,

Pacheco²,

Horvath³

1996

ApJ

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The method developed by Ra elt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, M c , from properties of the color-magnitude diagrams of Galactic globular clusters is employed. In the present study, we revise and update Ra elt's database, including also constraints from RR Lyrae pulsation, and nd that a small increase, by M c 0:01 0:015 M , cannot be ruled out with the present data and evolutionary models. Our new upper limits on M c are less restrictive than those previously obtained by Ra elt, as are the corresponding constraints on novel astroparticle phenomena which may a ect the evolution of low-mass red giants. Within the estimated uncertainties, however, the standard values of M c may also be acceptable. Ra elt's method does not rule out a low envelope helium abundance in globular cluster giants, though again the standard values are compatible with the available constraints. The in uence of a non-solar ratio for the -capture elements upon these results is also investigated. In addition, we review several aspects of the input physics employed in red giant stellar evolutionary calculations, with the purpose of evaluating possible sources of uncertainty in the value of the helium-core mass at the helium ash that is obtained from evolutionary computations, such as: heat conduction by electrons in the degenerate core; Coulomb e ects upon the Equation of State; triple-reaction rates and screening factors; neutrino emission rates, both standard and enhanced by a possible non-zero magnetic moment; stellar rotation; microscopic element di usion; and energy losses by axions and Weakly Interacting Massive Particles.

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“…For further calculations see, e.g., Refs 60,203,228,229,232,248,250,254,255,256,257,258,259. and references therein.…”

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confidence: 99%

The Path to Improved Reaction Rates for Astrophysics

Rauscher

2011

Int. J. Mod. Phys. E

144

337

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This review focuses on nuclear reactions in astrophysics and, more specifically, on reactions with light ions (nucleons and α particles) proceeding via the strong interaction. It is intended to present the basic definitions essential for studies in nuclear astrophysics, to point out the differences between nuclear reactions taking place in stars and in a terrestrial laboratory, and to illustrate some of the challenges to be faced in theoretical and experimental studies of those reactions. The discussion revolves around the relevant quantities for astrophysics, which are the astrophysical reaction rates. The sensitivity of the reaction rates to the uncertainties in the prediction of various nuclear properties is explored and some guidelines for experimentalists are also provided.Caminante, son tus huellas el camino, y nada más; Caminante, no hay camino, se hace camino al andar.Al andar se hace camino y al volver la vista atrás se ve la senda que nunca se ha de volver de pisar. Caminante, no hay camino sino estelas en la mar.

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Alpha clustering and the stellar nucleosynthesis of carbon

Abstract: Abstract:The astrophysical S-factor and reaction rates for the triple-alpha process are calculated in the direct-capture model. It is shown that the stellar carbon production is extremely sensitive to small variations in the N-N interaction.

Cited by 3 publications

References 10 publications

αα scattering in halo effective field theory

αα scattering in halo effective field theory

The Helium-Core Mass at the Helium Flash in Low-Mass Red Giant Stars: Observations and Theory

The Path to Improved Reaction Rates for Astrophysics

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