English

Statistical Properties of Photospheric Magnetic Elements Observed by SDO/HMI

Solar and Stellar Astrophysics 2017-07-31 v1

Abstract

Magnetic elements of the solar surface are studied in magnetograms recorded with the high-resolution Solar Dynamics Observatory / Helioseismic and Magnetic Imager . To extract some statistical and physical properties of these elements (e.g., filling factors, magnetic flux, size, lifetimes), the Yet Another Feature Tracking Algorithm (YAFTA), a region-based method, is employed. An area with 400×^{\prime\prime}\times400^{\prime\prime} was selected to investigate the magnetic characteristics during the year 2011. The correlation coefficient between filling factors of negative and positive polarities is 0.51. A broken power law fit was applied to the frequency distribution of size and flux. Exponents of the power-law distributions for sizes smaller and greater than 16 arcsec2^2 were found to be -2.24 and -4.04, respectively. The exponents of power-law distributions for fluxes smaller and greater than 2.63×\times1019^{19} Mx were found to be -2.11 and -2.51, respectively. The relationship between the size (SS) and flux (FF) of elements can be expressed by a power-law behavior in the form of SF 0.69S\propto F~^{0.69}. The lifetime and its relationship with the flux and size of quiet-Sun (QS) elements are studied during three days. The code detected patches with lifetimes of about 15 hours, which we call long-duration events. It is found that more than 95\% of the magnetic elements have lifetimes of less than 100 minutes. About 0.05\% of the elements were found with lifetimes of more than 6 hours. The relationships between the size (S), lifetime (T), and the flux (F) for patches in the QS, indicate the power-law relationships ST 0.25S\propto T~^{0.25} and FT 0.38F\propto T~^{0.38}, respectively. Executing a detrended fluctuation analysis of the time series of new emerged magnetic elements, we find a Hurst exponent of 0.82, which implies long-range temporal correlation in the system.

Keywords

Cite

@article{arxiv.1707.09291,
  title  = {Statistical Properties of Photospheric Magnetic Elements Observed by SDO/HMI},
  author = {Mohsen Javaherian and Hossein Safari and Neda Dadashi and Markus Josef Aschwanden},
  journal= {arXiv preprint arXiv:1707.09291},
  year   = {2017}
}

Comments

20 pages, 17 figures, submitted to Journal of Solar Physics