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

Castellanos Durán, J. S., Kleint, L., & Calvo-Mozo, B. (2018). A Statistical Study of Photospheric Magnetic Field Changes During 75 Solar Flares. The Astrophysical Journal, 852(1): 25. doi:10.3847/1538-4357/aa9d37.

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 Creators:
Castellanos Durán, Juan Sebastian1, 2, Author           
Kleint, L., Author
Calvo-Mozo, B., Author
Affiliations:
1International Max Planck Research School for Solar System Science at the University of Göttingen, Max Planck Institute for Solar System Research, Max Planck Society, Justus-von-Liebig-Weg 3, 37077 Göttingen, DE, ou_1832290              
2Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, Justus-von-Liebig-Weg 3, 37077 Göttingen, DE, ou_1832289              

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 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 (BLOS) changes during 18 X-, 37 M-, 19 C-, and 1 B-class flares using data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager. We investigated the properties of permanent changes, such as frequency, areas, and locations. We detected changes of BLOS in 59/75 flares. We find that strong flares are more likely to show changes, with all flares ≥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.

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Language(s): eng - English
 Dates: 2018-01-092018
 Publication Status: Published online
 Pages: -
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 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.3847/1538-4357/aa9d37
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Title: The Astrophysical Journal
Source Genre: Journal
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Publ. Info: Chicago, IL : University of Chicago Press for the American Astronomical Society
Pages: - Volume / Issue: 852 (1) Sequence Number: 25 Start / End Page: - Identifier: ISSN: 0004-637X
CoNE: https://pure.mpg.de/cone/journals/resource/954922828215_3