THE VARIATION OF RELATIVE MAGNETIC HELICITY AROUND MAJOR FLARES

被引:51
作者
Park, Sung-Hong [1 ,2 ]
Lee, Jeongwoo [1 ]
Choe, G. S. [3 ,4 ]
Chae, Jongchul [5 ,6 ]
Jeong, Hyewon [5 ,6 ]
Yang, Guo [1 ,2 ]
Jing, Ju [1 ,2 ]
Wang, Haimin [1 ,2 ]
机构
[1] New Jersey Inst Technol, Ctr Solar Terr Res, Newark, NJ 07102 USA
[2] Big Bear Solar Observ, Big Bear City, CA 92314 USA
[3] Kyung Hee Univ, Dept Astron & Space Sci, Yongin 449701, South Korea
[4] Princeton Plasma Phys Lab, Princeton, NJ 08543 USA
[5] Seoul Natl Univ, Astron Program, Dept Phys & Astron, Seoul 151742, South Korea
[6] Seoul Natl Univ, Dept Phys & Astron, FPRD, Seoul 151742, South Korea
基金
美国国家科学基金会;
关键词
Sun: flares; Sun: magnetic fields;
D O I
10.1086/591117
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have investigated the variation of magnetic helicity over a span of several days around the times of 11 X-class flares which occurred in seven active regions (NOAA 9672, 10030, 10314, 10486, 10564, 10696, and 10720) using the magnetograms taken by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). As a major result we found that each of these major flares was preceded by a significant helicity accumulation, (1.8-16) x 10(42) Mx(2) over a long period (0.5 to a few days). Another finding is that the helicity accumulates at a nearly constant rate, (4.5-4.8) x 10(40) Mx(2) hr(-1), and then becomes nearly constant before the flares. This led us to distinguish the helicity variation into two phases: a phase of monotonically increasing helicity and the following phase of relatively constant helicity. As expected, the amount of helicity accumulated shows a modest correlation with time-integrated soft X-ray flux during flares. However, the average helicity change rate in the first phase shows even stronger correlation with the time-integrated soft X-ray flux. We discuss the physical implications of this result and the possibility that this characteristic helicity variation pattern can be used as an early warning sign for solar eruptions.
引用
收藏
页码:1397 / 1403
页数:7
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