Relationship between Rotating Sunspots and Flares |
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Authors: | Yin Zhang Jihong Liu Hongqi Zhang |
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Institution: | (1) National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China |
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Abstract: | Active Region (AR) NOAA 10486 was a super AR in the declining phase of solar cycle 23. Dominated by the rapidly rotating positive
polarity of an extensive δ sunspot, it produced several powerful flare-CMEs. We study the evolution and properties of the rotational motion of the major
poles of positive polarities and estimate the accumulated helicity injected by them. We also present two homologous flares
that occurred in the immediate periphery of the rotating sunspots. The main results are as follows: i) anticlockwise rotational motions are identified in the main poles of positive polarities in the AR; the fastest of them
is about 220° for six days. ii) The helicity injection inferred from such rotational motion during the interval from October 25 to 30 is about − 3.0×1043 Mx2, which is comparable that calculated by the local correlation tracking (LCT) method (− 5.2×1043 Mx2) in the whole AR. It is suggested that both methods reveal the essential topological properties of the AR, even if the former
includes only the major poles and the fine features of the magnetic field are neglected. iii) It is found that there is a good spatial and temporal correspondence between the onset of two homologous CME-associated
flares and the rotational motion of sunspots. This suggests that the rotational motions of sunspots not only relate to the
transport of magnetic energy and complexity from the low atmosphere to the corona but may also play a key role in the onset
of the homologous flares.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. |
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Keywords: | Sun: sunspot Sun: magnetic field Sun: activity |
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