Relationship between rotating sunspots and flare productivity

Abstract

To understand both the effects of dynamo and the nature of flaring activity, we identified rotating sunspots and then classified them into six types by using the data of Transition Region and Coronal Explorer and Solar and Heliospheric Observatory/Michelson Doppler Imager in Solar Cycle 23. The classification is made by their rotating directions and relative positions (leading or following sunspots), while the corresponding samples are given. The statistics of flares relevant to these sunspots are presented to show the relationship between different types of rotating sunspots and their flare productivity. It is found that some types of rotating sunspots are in favour of producing flares, and, outstandingly those active regions with sunspots of rotating direction opposite to the differential rotation have much higher strong (X-class) flare productivity. Furthermore, we found that the ratio of the number of flares defined in this paper is inconsistent to the number evolution of the six types of rotating sunspots. The maximum ratios of the six types except type VI appear after the maximum year. Additionally, there are total 60 possible patterns of rotating sunspots belonging to the six types, among which 35 patterns are found but 25 patterns remain to be discovered in other solar cycles. These results not only place further constraints on the dynamo theory but also reveal that the rotation motions of sunspots can be greatly helpful to the energy buildup of solar flares. © 2008 RAS.