The Astrophysical Journal
We have explored the impact of magnetic fields on the determination of the solar photospheric oxygen and iron abundances using three-dimensional radiation–magnetohydrodynamic (MHD) simulations of convection. Specifically, we examined differences in abundance deduced from three classes of atmospheres simulated with theMURaM code: a pure hydrodynamic (HD) simulation, anMHDsimulation with a local dynamomagnetic field that has saturatedwith an unsigned vertical field strength of 80Gat τ = 1, and anMHDsimulationwith an initially imposed vertical mean field of 80 G. We use differential equivalent width analysis for diagnosing abundances derived from five oxygen and four iron lines of differing wavelength, oscillator strength, excitation potential, and Land´ e g-factor, and find that the morphology of the magnetic field is important to the outcome of abundance determinations. The largest deduced abundance differences are found in the vertical mean field simulations, where theOi and Fe i abundance corrections compared to the pureHDcase are∼+0.011 dex and +0.065 dex respectively. Small scale unresolved field resulting from the local dynamo has a smaller impact on abundance determinations, with corrections of −0.0001 dex and +0.0044 dex in the magnetized compared to the pure HD simulations.While the overall influence of magnetic field on abundance estimates is found to be small, we stress that such estimates are sensitive not only to the magnitude of magnetic field but also to its morphology.
Moore, C. S.; Uitenbroek, H.; Rempel, M.; Criscuoli, S.; and Rast, Mark P., "The Effects of Magnetic Field Morphology on the Determination of Oxygen and Iron Abundances in the Solar Photosphere" (2015). Astrophysical & Planetary Sciences Faculty Contributions. 28.