A Statistical Study of Photospheric Magnetic Field Changes During 75 Solar Flares

Abstract

Abrupt and permanent changes of photospheric magnetic fields have been observed during solar flares. The changes seem to be linked to the reconfiguration of magnetic fields, but their origin is still unclear. We carried out a statistical analysis of permanent line-of-sight magnetic field ($B_{\mathrm{LOS}}$) changes during 18 X-, 37 M-, 19 C- and 1 B-class flares using data from Solar Dynamics Observatory/Helioseismic and Magnetic Imager. We investigated the properties of permanent changes, such as frequency, areas, and locations. We detected changes of $B_{\mathrm{LOS}}$ in 59/75 flares. We find that strong flares are more likely to show changes, with all flares $\ge$ M1.6 exhibiting them. For weaker flares, permanent changes are observed in 6/17 C-flares. 34.3\% of the permanent changes occurred in the penumbra and 18.9\% in the umbra. Parts of the penumbra appeared or disappeared in 23/75 flares. The area where permanent changes occur is larger for stronger flares. Strong flares also show a larger change of flux, but there is no dependence of the magnetic flux change on the heliocentric angle. The mean rate of change of flare-related magnetic field changes is 20.7 Mx cm${}^{-2}$ min${}^{-1}$. The number of permanent changes decays exponentially with distance from the polarity inversion line. The frequency of the strength of permanent changes decreases exponentially, and permanent changes up to 750 Mx cm${}^{-2}$ were observed. We conclude that permanent magnetic field changes are a common phenomenon during flares, and future studies will clarify their relation to accelerated electrons, white light emission, and sunquakes to further investigate their origin.

Piblished in ApJ

References in corpus (10)

• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Abrupt changes in photospheric magnetic and Lorentz-force vectors during neutral-line flares
• First Detection of Chromospheric Magnetic Field Changes During an X1-Flare
• The Relationship between the Sudden Change of the Lorentz Force and the Magnitude of Associated Flares
• Structure and Evolution of Magnetic Fields Associated with Solar Eruptions (Invited Review)
• Three-dimensional Magnetic Restructuring in Two Homologous Solar Flares in the Seismically Active NOAA AR 11283
• On the Origin of a Sunquake during the 29 March 2014 X1 Flare
• Estimation of the magnetic flux emergence rate in the quiet Sun from Sunrise data
• Magnetic Flux Change and Cancellation Associated with X-class and M-class Flares
• Abrupt Longitudinal Magnetic Field Changes and Ultraviolet Emissions Accompanying Solar Flares

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