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Solar oxygen abundance

Carlsson, Mats; Reiners, Ansgar; Bergemann, Maria +10 more

Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New atomic models of O and Ni are used to perform non-local thermodynamic equilibrium (NLTE) calculations with 1D hydrostatic (MARCS) and 3D hydrodynamical (Stagger and Bifrost) models. The Bifrost 3D MHD s…

Signature and escape of highly fractionated plasma in an active region

Brooks, David H.; Yardley, Stephanie L.

Accurate forecasting of space weather requires knowledge of the source regions where solar energetic particles (SEP) and eruptive events originate. Recent work has linked several major SEP events in 2014, January, to specific features in the host active region (AR 11944). In particular, plasma composition measurements in and around the footpoints …

Thermodynamic evolution of a sigmoidal active region with associated flares

Mulay, Sargam M.; Tripathi, Durgesh; Mason, Helen

Active regions often show S-shaped structures in the corona called sigmoids. These are highly sheared and twisted loops formed along the polarity inversion line. They are considered to be one of the best pre-eruption signatures for CMEs. Here, we investigate the thermodynamic evolution of an on-disc sigmoid observed during 2015 December 24-28. For…

Relationship between magnetic field properties and statistical flow using numerical simulation and magnetic feature tracking on solar photosphere

Oba, T.; Iida, Y.; Hotta, H. +1 more

We perform radiative magnetohydrodynamic calculations for the solar-quiet region to investigate the dependence of statistical flow on magnetic properties and the three-dimensional structure of magnetic patches in the presence of large-scale flow that mimics differential rotation. It has been confirmed that strong magnetic field patches move faster…