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Abstract: Magnetic elements are thought to be described by flux tube models, and arewell reproduced by MHD simulations. However, these simulations are onlypartially constrained by observations. We observationally investigate therelationship between G-band bright points and magnetic structures to clarifyconditions, which make magnetic structures bright in G-band. The G-bandfiltergrams together with magnetograms and dopplergrams were taken for a plageregion covered by abnormal granules as well as ubiquitous G-band bright points,using the Swedish 1-m Solar Telescope SST under very good seeing conditions.High magnetic flux density regions are not necessarily associated with G-bandbright points. We refer to the observed extended areas with high magnetic fluxdensity as magnetic islands to separate them from magnetic elements. Wediscover that G-band bright points tend to be located near the boundary of suchmagnetic islands. The concentration of G-band bright points decreases withinward distance from the boundary of the magnetic islands. Moreover, G-bandbright points are preferentially located where magnetic flux density is higher,given the same distance from the boundary. There are some bright points locatedfar inside the magnetic islands. Such bright points have higher minimummagnetic flux density at the larger inward distance from the boundary.Convective velocity is apparently reduced for such high magnetic flux densityregions regardless of whether they are populated by G-band bright points ornot. The magnetic islands are surrounded by downflows.These results suggestthat high magnetic flux density, as well as efficient heat transport from thesides or beneath, are required to make magnetic elements bright in G-band.



Author: R. Ishikawa, S. Tsuneta, Y. Kitakoshi, Y. Katsukawa, J. A. Bonet, S. Vargas Domínguez, L. H. M. Rouppe van der Voort, Y. Sakamot

Source: https://arxiv.org/







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