The Solar Heavy Element Abundances: I. Constraints from Stellar Interiors

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 Fe/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. Subject headings: Atomic data opacity stars:diffusions stars: interior stars: evolution solar abundances solar calibration