The state of 7Be in the core of the Sun and the solar neutrino flux

Nir J. Shaviv, Giora Shaviv*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The exact ionization state of 7Be in the solar core is crucial for the precise prediction of the solar 8B neutrino flux. We therefore examine the effect of pressure ionization on the ionization state of 7Be and all elements with 12 ≥ Z ≥ 4. We show that under the conditions prevailing in the solar core one has to consider the effect of the nearest neighbour on the electronic structure of a given ion. To this goal, we first solve the Schrödinger and then the Kohn-Sham equations for an ion immersed in a dense plasma under conditions for which the mean interparticle distance is smaller than the Debye radius. The question of which boundary conditions should be imposed on the wavefunction is discussed, examined and found to be crucial. Contrary to previous estimates showing that beryllium is partially ionized, we find that it is fully ionized. As a consequence, the predicted rate of the 7Be + e- reaction is reduced by 20-30 per cent, depending on the details of the solar model. Because 7Be is a trace element, its total production is controlled by the unchanged 4He -3 He reaction rate, and its destruction is determined by the rate of electron capture. As the latter rate decreases when the beryllium is fully ionized (relative to the case of partially ionized Be), the estimate for the abundance of 7Be increases and with it the 8B neutrino flux. The increase in ØV(8B) is by about 20-30 per cent. The neutrino flux due to 7Be electron capture remains effectively unchanged because the change in the rate is compensated for by a change in the abundance. Hence the prediction for the ratio of Øv(8B) Øv( 7Be) changes as well.

Original languageAmerican English
Pages (from-to)119-128
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 1 May 2003


  • Atomic processes
  • Equation of state
  • Plasmas
  • Sun: Interior


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