The chemical make-up of the Sun: A 2020 vision

Context. The chemical composition of the Sun is a fundamental yardstick in astronomy, relative to which essentially all cosmic objects are referenced. As such, having accurate knowledge solar elemental abundances crucial for an extremely broad range topics. Aims. We reassess 83 long-lived elements, using highly realistic modelling and state-of-the-art spectroscopic analysis techniques coupled with best available atomic data observations. Methods. basis our three-dimensional (3D) radiative-hydrodynamical model surface convection atmosphere, reproduces full arsenal key observational diagnostics. New complete comprehensive 3D spectral line formation calculations taking into account departures from local thermodynamic equilibrium (non-LTE) presented Na, Mg, K, Ca, Fe atoms reliable radiative collisional data. Our newly derived C, N, O based on non-LTE permitted forbidden lines as well LTE total 879 molecular transitions CH, C 2 , CO, NH, CN, OH. Previous 3D-based another 50 elements re-evaluated updated data, stringent selection lines, improved consideration blends, new literature. For where determinations quiet not possible, recommended revisited complementary methods, including helioseismology (He), wind Genesis sample return mission (noble gases), sunspot observations (four elements), measurements most primitive meteorites (15 elements). Results. confirms relatively low obtained previous studies: log ? = 8.46 ± 0.04, N 7.83 0.07, 8.69 0.04. Excellent agreement between indicators achieved O, but imply lower abundance than unknown reasons. revised other also typically agree previously values, only Li, F, Ne, Cl, Kr, Rb, Rh, Ba, W, Ir, Pb differing by more 0.05 dex. here-advocated present-day photospheric metal mass fraction slightly higher value, mainly due Ne measurements: X 0.7438 0.0054, Y 0.2423 Z 0.0139 0.0006, / 0.0187 0.0009. Overall, those CI chondritic meteorites, we identify correlation condensation temperature such that moderately volatile enhanced ?0.04 dex chondrites refractory possibly depleted ?0.02 dex, conflicting conventional wisdom past half-century. Instead, closely resembles fine-grained matrix CM expected exception elements. Conclusions. Updated proto-solar isotopes. so-called problem – persistent discrepancy interior models constructed metallicity similar advocated here remains intact abundances, suggesting shortcomings computed opacities and/or treatment mixing below zone existing standard models. uncovered trend yet understood likely imprinted planet formation, especially since opposite sign observed twins.