Solar opacity, neutrino signals and helioseismology

In connection with the recent suggestion by Tsytovich et al. [1] that opacity in the solar core could be overestimated, we consider the following questions: i) What would a 10% opacity reduction imply for the solar neutrino puzzle? ii) Is there any hope of solving the solar neutrino puzzle by changing opacity? iii) Is a 10% opacity reduction testable with helioseismological data? Recently Tsytovich et al. [1] reviewed corrections to the theory of photon transport in a dense hot plasma and claimed that previous calculations overestimate solar opacity κ near solar center by about 10%. More generally the accuracy of the calculated opacity in the solar core is controversial: the characteristic difference between the calculations of the Livermore and Los Alamos groups is about (2–5)% [2] and essentially on these grounds Bahcall and Pinsonneault [3] estimate a (1σ) uncertainty of about 2.5%. On the other hand, TurckChièze et al. [4] argued the uncertainty to exceed 5%, a point criticized in [3]. It is worth recalling that, for the conditions of the solar interior, no experimental check is available and the estimates of accuracy originate essentially from theoretical arguments. In this short note we consider thus the following questions: i) What would 10% opacity reduction imply for the solar neutrino puzzle? ii) Is there any hope of solving the solar neutrino puzzle by changing opacity? iii) Is a 10% opacity reduction testable with helioseismological data? In our analysis we assume a uniform reduction of opacity, i.e. κ(ρ, T, ...)→ xκ(ρ, T, ...), where the factor x is independent of density, temperature and chemical composition (other approaches to the effect of solar opacity on neutrino fluxes are reported, for instance, in refs. [5–7]). The assumption of uniform opacity variations is clearly ad hoc, to restrict the possible solar models. Nevertheless, it can be used as a first attempt to analyze the effects of the Tsytovich et al.proposal, for the following reasons: 1) the plasma effect advocated in [1] are mainly governed by the quantity δ = cω pl/v 2 Tω , see [1] for notations. As δ ∝ ne/T , it stays approximately constant along the solar profile. ∗[email protected]