On the relationship between sunspot structure and magnetic field changes associated with solar flares

Abstract

Many previous studies have shown that magnetic fields as well as sunspot structures present rapid and irreversible changes associated with solar flares. In this paper we first use five X-class flares observed by SDO/HMI to show that not only the magnetic fields and sunspot structures do show rapid, irreversible changes but also these changes are closely related, both spatially and temporally. The magnitudes of the correlation coefficients between the temporal variations of horizontal magnetic field and sunspot intensity are all larger than 0.90, with a maximum value of 0.99 and an average value of 0.96. Then using four active regions in quiescent times, three observed and one simulated, we show that in sunspot penumbra regions there also exists a close correlation between sunspot intensity and horizontal magnetic field strength, in addition to the well-known one between sunspot intensity and normal magnetic field strength. Connecting these two observational phenomena, we show that the sunspot structure change and the magnetic field change are the two facets of the same phenomena of solar flares, one change might be induced by the change of the other due to a linear correlation between sunspot intensity and magnetic field strength out of a local force balance.

References in corpus (4)

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Cited by in corpus (8)

• The Statistical Relationship between White-light Emission and Photospheric Magnetic Field Changes in Flares
• Observations of white-light flares in NOAA active region 11515: high occurrence rate and relationship with magnetic transients
• Evolution of Photospheric Vector Magnetic Field Associated with Moving Flare Ribbons As Seen By GST
• A Survey of Changes in Magnetic Helicity Flux on the Photosphere During Relatively Low Class Flares
• Relationship between Successive Flares in the Same Active Region and Space-Weather HMI Active Region Patch (SHARP) Parameters
• Sunspots rotation and magnetic transients associated with flares in NOAA AR 11429
• A Statistical Study of the Magnetic Imprints of X-Class Solar Flares
• Continuum enhancements, line profiles and magnetic field evolution during consecutive flares