THE EFFECTS OF MAGNETIC FIELD MORPHOLOGY ON THE DETERMINATION OF OXYGEN AND IRON ABUNDANCES IN THE SOLAR PHOTOSPHERE

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...

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Bibliographic Details
Published in:The Astrophysical journal 2015-02, Vol.799 (2), p.1-6
Main Authors: Moore, Christopher S, Uitenbroek, Han, Rempel, Matthias, Criscuoli, Serena, Rast, Mark P
Format: Article
Language:English
Subjects:
Abundance
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
CONVECTION
CORRECTIONS
ELEMENT ABUNDANCE
EXCITATION
GRANULATION
IRON
LANDE FACTOR
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MEAN-FIELD THEORY
MHD
MORPHOLOGY
OSCILLATOR STRENGTHS
OXYGEN
PHOTOSPHERE
Simulation
SUN
THREE-DIMENSIONAL CALCULATIONS
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Summary: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 the MURaM code: a pure hydrodynamic (HD) simulation, an MHD simulation with a local dynamo magnetic field that has saturated with an unsigned vertical field strength of 80 G at [tau] = 1, and an MHD simulation with 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 Lande 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 the O I and Fe I abundance corrections compared to the pure HD case 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.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/799/2/150