The Screened Nuclear Reaction Rates and the Solar Neutrino Puzzle

Dzitko, H.; Turck‐Chièze, S.; Delbourgo-Salvador, P.; Lagrange, Ch.

doi:10.1086/175887

Cited by 69 publications

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“…All in all, the results are rather stable with respect to the changements we have introduced as long as diffusion is neglected. The new equation of state (a → b) and the improved opacity (b → c) yield a somehow smaller 8 B (and also 7 Be and CNO) neutrino flux as a consequence of the smaller central temperature, see also Turck-Chièze & Lopes (1993) and Dzitko et al (1995) where a similar result is obtained. On the other hand, due to the higher central temperature, model (d) has significantly higher 8 B and CNO neutrino fluxes.…”

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confidence: 54%

“…The models with Straniero EOS have a higher central pressure and a higher central temperature, and correspondingly a higher initial helium abundance. The effect of an understimated Coulomb correction was discussed in Turck-Chièze & Lopes (1993) and in Dzitko et al (1995). Note that the helium abundance is higher than the helioseismological determination by more than 2σ.…”

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confidence: 95%

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Updating standard solar models

Ciacio

Degl’Innocenti

Ricci

1997

Astron. Astrophys. Suppl. Ser.

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Abstract. We present an updated version of our standard solar model (SSM) where helium and heavy elements diffusion is included and the improved OPAL equation of state (Rogers 1994;Rogers et al. 1996) is used. In such a way the EOS is consistent with the adopted opacity tables, from the same Livermore group, an occurrence which should further enhance the reliability of the model. The results for the physical characteristics and the neutrino production of our SSM are discussed and compared with previous works on the matter.Key words: the Sun: evolution -the Sun: generalthe Sun: particle emission In the last decades evolutionary computations of Standard Solar Models (SSM) played a fundamental role in understanding the inner solar structure and, in particular, in approaching the well known problem of solar neutrinos. Bahcall & Pinsonneault (1995; hereafter BP95) have already shown that to reach the agreement with observational evidence given by helioseismology one needs, in addition to the best available input physics, an accurate treatment of element diffusion all along the solar structure. The recent availability of an improved equation of state (EOS), as given by the OPAL group (Rogers 1994;Rogers et al. 1996) obviously suggests to investigate the influence of such an improvement on SSM. In this paper we discuss this scenario, presenting an updated SSM resulting from a recent version of FRANEC (Frascati Raphson Newton Evolutionary Code), where helium and heavy elements diffusion is included and the OPAL equation of state is used. Note that in such a way the EOS is consistent with the adopted opacity tables, from the same Livermore group (Rogers & Iglesias 1995), an occurrence which should further enhance the reliability of the model. In addition, updated values of the relevant nuclear cross Send offprint requests to: S. Degl'Innocenti, Dipartimento di Fisica Università scilla@vaxfe.fe.infn.it sections are used and more refined values of the solar constant and age (BP95) are adopted.Before entering into the argument, let us recall that in recent years helioseismology has added important pieces of information on the solar structure, producing severe tests for standard solar model calculations. According to Christensen-Dalsgaard et al. (1993) one can accurately determine the depth of the solar convective zone and the speed of sound at its bottom: The much smaller errors often quoted, reflect the observational frequency errors only. The results actually depend on the method of inversion and on the starting physical inputs (e.g. the EOS), see RCVD96.Note that, since in building a SSM one is dealing with three free parameters (mixing length, original He content and original Z/X), with these three additional constraints (R b , c b and Y photo ) no free parameter is left for SSM builders.After discussing the effect of the physical inputs, we compare our SSM with other recent solar model calculations, all including diffusion of helium and heavy elements, finding an excellent agreement. We present neutrino fluxes and the...

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confidence: 54%

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confidence: 95%

Updating standard solar models

Ciacio

Degl’Innocenti

Ricci

1997

Astron. Astrophys. Suppl. Ser.

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“…An extensive review on the screening of nuclear reactions in the Sun can be found in Dzitko & (1995), Turck-Chie`ze where various approximations to the mean Ðeld electrostatic potential of an ion in the plasma are discussed and their e †ects on the solar neutrino Ñux predictions assessed. The authors reach the conclusion that "" the solar neutrino discrepancy between experiments and predictions could be considerably reduced ÏÏ with a proper treatment of the screening.…”

Section: Introductionmentioning

confidence: 99%

“…The authors reach the conclusion that "" the solar neutrino discrepancy between experiments and predictions could be considerably reduced ÏÏ with a proper treatment of the screening. In all the approximations discussed by Dzitko & (1995) the static approximation is assumed Turck-Chie`ze and no dynamic e †ects are taken into account.…”

Section: Introductionmentioning

confidence: 99%

The Electrostatic Screening of Nuclear Reactions in the Sun

Shaviv

Shaviv²

2001

ApJ

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We apply the method of Shaviv & Shaviv to evaluate from Ðrst principles the plasma screening correction to the rate of nuclear reactions under conditions similar to those prevailing in the present-day Sun. We calculate the screening factor for the p-p chain and the CN cycle nuclear reactions. We Ðnd the following :1. The mean Ðeld approximation la is not strictly valid under the conditions prevaila`Debye-Huckel ing in the core of the Sun. A kinetic approach should be implemented.2. The mean energy exchange between any two scattering particles and the plasma is positive for low relative kinetic energies and negative for high relative kinetic energies. The turnover in a pure hydrogen plasma occurs at about for the p-p reaction, for example, and changes E kin~rel B 2kT \ E Gamow B 6kT with the particular reaction. The net energy exchange, namely, the sum over all pairs of scattering particles in the system, vanishes in equilibrium.3. The turnover from energy gain to energy loss of the scattering particles is generally below the Gamow peak. The details depend on the masses of the interacting particles relative to the mass of the particles in the ambient plasma.4. The Ñuctuations and nonspherical e †ects are crucial in a †ecting the screening. We investigate the source of the Ñuctuations and their power spectrum. In view of the particular behavior of the Ñuctua-tions we derive the net e †ect of the plasma on the reaction rate for each reaction investigated here.5. The derived screening corrections, which are a function of the relative kinetic energy and depend on the environment, are averaged over the distribution of relative velocities and cross section to obtain the total screening correction. The preliminary results are obtained in two easy-to-handle limits. The p-p reaction is found to be enhanced relative to reaction in vacuum, while higher Z reactions, like the Be7 ] p reaction, are suppressed relative to the classical Salpeter theory.6. In the Appendix we show the connection between the screening and the coefficients in the FokkerPlanck equation. We use the same computer program to calculate the coefficient in the Fokker-Planck equation and Ðnd a behavior that supports the present Ðndings of the general values and behavior of the screening.

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“…This compilation shows a general accuracy of about 10% on pp chain reactions and slightly worse on CNO cycle. Several studies have also been dedicated to the problem of screening on not totally weak nor strong coupling plasmas (Dzitko et al 1995;Gruzinov 1998;Shavivand Shaviv 1999, 2000Tsytovich and Bornatici, 2000). A large and continuous effort has been devoted to the detailed calculations of opacity coefficients in order to get coherence between equation of state and opacity as well as expanding the number of elements included in the calculations.…”

Section: Fundamental Physicsmentioning

confidence: 99%

Recent Progress in Solar or Stellar Interior Modelling

Turck‐Chièze¹

2001

Symp. - Int. Astron. Union

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Abstract. Acoustic modes are well-suited probes to check the internal stellar structure and bring interesting constraints on turbulence regions, mixing in stellar interiors and magnetic fields. The SOHO satellite, through the helioseismic instruments GOLF, MDI and VIRGO, has significantly improved the knowledge of these modes owing to an excellent duty cycle (greater than 90%) and the capability to detect very lowamplitude modes, down to 3 tutu]». Five years of the SOHO misson guarantee an accurate view of the solar interior, weakly dependent on the turbulent surface, from the energy-generating core to the surface.The recent results allow us to verify some of the theoretical assumptions of stellar modelling. The tachocline layers, located in a narrow region at the base of the convection zone, support an hydro (or magnetohydro) dynamical instability which induces mixing and results in 7Li depletion in accordance with photospheric observations. On the contrary, central mixing is not favoured by the present observations. Nuclear reaction rates of the pp chain are now constrained by the behaviour of the sound speed and density. Doppler velocity measurements appear as an excellent technique to follow in real time the temporal evolution of the luminosity produced in the core. Some puzzling questions about dynamical effects in stellar plasmas can now start to be addressed for the first time. The theoretical neutrino emissions can be now directly deduced from our helioseismic vision of the energy-generating core.Nowadays, helioseismology provides a dynamical vision of the external half of the Sun (20% in mass), as a result of the extraction of the sound speed, density, rotation profiles and of the time evolution of velocity measurements. Below, the classical static vision of the nuclear region persists because of the poor spatial resolution offered by acoustic modes (±6% in radius, 10% in mass) and the long integration time (several years). Gravity modes will be extremely useful to improve the spatial resolution in the radiative region. The extended observations with the SOHO satellite may be extremely useful to detect some of these modes.

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The Screened Nuclear Reaction Rates and the Solar Neutrino Puzzle

Cited by 69 publications

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Updating standard solar models

Updating standard solar models

The Electrostatic Screening of Nuclear Reactions in the Sun

Recent Progress in Solar or Stellar Interior Modelling

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