engleski

Turbulent Diffusion Derived from the Motions of SDO/AIA Coronal Bright Points

Diffusion of magnetic elements on the Sun has an important role in current solar dynamo models as a part of the mechanism for redistribution of the magnetic field and as an important part for maintaining the solar activity cycle. The main goal is to determine the character of solar magnetic diffusivity and a value of the diffusion coefficient by analyzing the motions of coronal bright points (CBPs) within the frame of the random walk model. We tracked positions of CBPs in Solar Dynamics Observatory/Atmospheric Imaging Assembly images for a period of 5 months and examined their displacement spectrum. We calculated spectral index and diffusion coefficient from the spectrum and investigated their variation with temporal and spatial scale. For the first time, variations of the spectral index with heliographic latitude and time were analyzed. Our results indicate subdiffusion with the spectral index γ = 0.70 ± 0.01 and the corresponding diffusion coefficient with a value decreasing from 400 to 100 km^2 s^{;‑1}; for temporal scales of 10^3–10^5 s and spatial scales of (1.5–7) × 10^3 km. Seemingly random variations around the mean value of spectral index were found, with peak-to-peak amplitudes <0.30 with time and <0.10 with latitude. The main conclusion is that CBP motions are consistent with a subdiffusion process.

convection ; diffusion ; Sun: corona ; Sun: UV radiation

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