2022/07/21 by Markus J. Aschwanden, Aschwanden, Markus J., Nived Vilangot Nhalil +1
Economics, Econometrics and Finance · Physics and Astronomy · #Complex Systems and Time Series Analysis #FOS: Physical sciences #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #Statistical Mechanics and Entropy
paper · pdf · doi:10.48550/arxiv.2207.12894
openalex publication_date 2022/07/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
While previous work explored the fractality and self-organized criticality (SOC) of flares and nanoflares in wavelengths emitted in the solar corona (such as in hard X-rays, soft X-rays, and EUV wavelenghts), we focus here on impulsive phenomena in the photosphere and transition region, as observed with the \sl Interface Region Imaging Spectrograph (IRIS) in the temperature range of Te ≈ 104-106 K. We find the following fractal dimensions (in increasing order): DA=1.21 ± 0.07 for photospheric granulation, DA=1.29 ± 0.15 for plages in the transition region, DA=1.54 ± 0.16 for sunspots in the transition region, DA=1.59 ± 0.08 for magnetograms in active regions, DA=1.56 ± 0.08 for EUV nanoflares, DA=1.76 ± 0.14 for large solar flares, and up to DA=1.89 ± 0.05 for the largest X-class flares. We interpret low values of the fractal dimension (1.0 \lapprox DA \lapprox 1.5) in terms of sparse curvi-linear flow patterns, while high values of the fractal dimension (1.5 \lapprox DA \lapprox 2.0) indicate near space-filling transport processes, such as chromospheric evaporation. Phenomena in the solar transition region appear to be consistent with SOC models, based on their size distributions of fractal areas A and (radiative) energies E, which show power law slopes of αAobs=2.51 ± 0.21 (with αAtheo=2.33 predicted), and αEobs=2.03 ± 0.18 (with αEtheo=1.80 predicted).