Abstract
Allδ-sunspots from September 1986 to December 1992 in solar cycle 22 are used to investigate the characteristics ofδ-sunspots and the relationship betweenδ-sunspots and X-class X-ray flares. The main results of this statistical study are as follows.
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(1)
The earlier discoveries on the formation and disintegration patterns ofδ-sunspots (Tang, 1983; Zirin and Liggett, 1987; Zirin, 1988) are confirmed. In a general sense, allδ-sunspots form from the penetration of two different dipoles. Delta-sunspots could be disintegrated byin situ flux cancellation. In addition, someδ-sunspots become separated by the sliding apart of opposite polarities.
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(2)
A prominent characteristic ofδ-sunspots is the imbalanced flux between the two polarities. A sample of 58δ-sunspots observed by the Solar Magnetic Field Telescope at Huairou, in which there are one or more X-class flares, maintains an average flux ratio of 6.6 between the majority and minority polarities. Unlike the early results of Tang (1983), two-third of them show a dominant flux from the preceding spots.
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(3)
The number ofδ-sunspots seems to be an index of solar activity. More than 95% of X-class X-ray flares take place in active regions ofδ-sunspots; while 23% ofδ-sunspots are generators of X-class X-ray flares. The productivity of X-class flares is closely correlated to the lifetime ofδ-sunspots in this manner:P xxf = −0.12 + 0.02T Emphasis>/2 δ .
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Shi, Z., Wang, J. Delta-sunspots and X-class flares. Sol Phys 149, 105–118 (1994). https://doi.org/10.1007/BF00645181
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DOI: https://doi.org/10.1007/BF00645181