Using the code autostructure, extensive calculations of inner-shell atomic data have been made for the chemical elements He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. The results are used to obtain updated opacities from the Opacity Project (OP). A number of other improvements on earlier work have also been included. Rosseland-mean opacities from the OP are compared with those from OPAL. Differences of 5-10 per cent occur. The OP gives the 'Z-bump', at log(T) 5.2, to be shifted to slightly higher temperatures. The opacities from the OP, as functions of temperature and density, are smoother than those from OPAL. The accuracy of the integrations used to obtain mean opacities can depend on the frequency mesh used. Tests involving variation of the numbers of frequency points show that for typical chemical mixtures the OP integrations are numerically correct to within 0.1 per cent. The accuracy of the interpolations used to obtain mean opacities for any required values of temperature and density depends on the temperature-density meshes used. Extensive tests show that, for all cases of practical interest, the OP interpolations give results correct to better than 1 per cent. Prior to a number of recent investigations which have indicated a need for downward revisions in the solar abundances of oxygen and other elements, there was good agreement between properties of the Sun deduced from helioseismology and from stellar evolution models calculated using OPAL opacities. The revisions destroy that agreement. In a recent paper, Bahcall et al. argue that the agreement would be restored if opacities for the regions of the Sun with 2 × 106T 5 × 106 K (0.7-0.4 R) were larger than those given by OPAL by about 10 per cent. In the region concerned, the present results from the OP do not differ from those of OPAL by more than 2.5 per cent

We perform a quantitative analysis of the solar composition problem by using a statistical approach that allows us to combine the information provided by helioseimic and solar neutrino data in an effective way. We include in our analysis the helioseismic determinations of the surface helium abundance and of the depth of the convective envelope, the measurements of the 7 Be and 8 B neutrino fluxes, the sound speed profile inferred from helioseismic frequencies. We provide all the ingredients to describe how these quantities depend on the solar surface composition and to evaluate the (correlated) uncertainties in solar model predictions. We include errors sources that are not traditionally considered such as those from inversion of helioseismic data. We, then, apply the proposed approach to infer the chemical composition of the Sun. We show that the opacity profile of the Sun is well constrained by the solar observational properties. In the context of a two parameter analysis in which elements are grouped as volatiles (i.e. C, N, O and Ne) and refractories (i.e Mg, Si, S, Fe), the optimal composition is found by increasing the the abundance of volatiles by (45 ± 4) % and that of refractories by (19 ± 3) % with respect to the values provided by Asplund et al. (2009). This corresponds to the abundances ε O = 8.85 ± 0.01 and ε Fe = 7.52 ± 0.01. As an additional result of our analysis, we show that the observational data prefer values for the input parameters of the standard solar models (radiative opacities, gravitational settling rate, the astrophysical factors S 34 and S 17 ) that differ at the ∼ 1σ level from those presently adopted.

The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which in turn leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convection zone depth and helium abundance combined with stellar interiors models can be used to define the goodness of fit rigorous for a given chemical composition. After a detailed examination of the errors in the theoretical models we conclude that models constructed with the older and higher solar abundances are consistent (within 2σ) with the seismic data. However, models constructed with the proposed new low abundance scale are strongly disfavored, disagreeing at the 15σ level. We then use the sensitivity of the seismic properties to abundance changes to invert the problem and infer a seismic solar heavy element abundance mix with two components: meteoritic abundances, and the light metals CNONe. Seismic degeneracies between the best solutions for the elements arise for changes in the relative CNONe abundances and their effects are quantified. We obtain F e/H = 7.50+/−0.045+/−0.003(CNNe) and O/H = 8.86 + / −0.041 + / −0.025(CNNe) on the logarithmic scale where H = 12 for the relative CNNe mixtures in the GS98 mixture; the second error term reflects the uncertainty in the overall abundance scale from errors in the C,N, and Ne abundances relative to oxygen. These are consistent within the errors with the previous standard solar mixture. However, the inferred solar oxygen abundance is in strong conflict with the low oxygen abundance inferred from the 3D hydro models. Changes in the Ne abundance can mimic changes in oxygen for the purposes of scalar constraints. However, models constructed with low oxygen and high neon are inconsistent with the solar sound speed profile. The implications for the solar abundance scale are discussed.