A Two-step Magnetic Reconnection in a Confined X-class Flare in Solar Active Region 12673

doi:10.3847/1538-4357/aaf3b7

	A Two-step Magnetic Reconnection in a Confined X-class Flare in Solar Active Region 12673
	Zou, Peng; Jiang, Chaowei; Feng, Xueshang; Zuo, Pingbing; Wang, Yi; Wei, Fengsi
刊名	ASTROPHYSICAL JOURNAL
	2019
卷号	870 期号:2 页码:97
关键词	Sun: coronal mass ejections (CMEs) Sun: flares Sun: magnetic fields
ISSN号	0004-637X
DOI	10.3847/1538-4357/aaf3b7
英文摘要	Solar flares are often associated with coronal eruptions, but there are confined ones without eruptions, even for some X-class flares. How such large flares occurred and why they are confined are still not well understood. Here we studied a confined X2.2 flare in NOAA Active Region 12673 on 2017 September 6. It exhibits two episodes of flare brightening with rather complex, atypical ribbons. Based on topology analysis of the extrapolated coronal magnetic field, we revealed that there is a two-step magnetic reconnection process during the flare. Prior to the flare, there is a magnetic flux rope (MFR) with one leg rooted in a rotating sunspot. Neighboring the leg is a magnetic null-point structure. The sunspot drives the MFR to expand, pushing magnetic flux to the null point, and reconnection is first triggered there. The disturbance from the null-point reconnection triggers the second reconnection, i.e., a tether-cutting reconnection below the rope. However, these two reconnections failed to produce an eruption, because the rope is firmly held by its strapping flux. Furthermore, we compared this flare with an eruptive X9.3 flare in the same region 2 hr later, which has a similar MFR configuration. The key difference between them is that, for the confined flare, the MFR is fully below the threshold of torus instability, whereas for the eruptive one, the MFR reaches entirely above the threshold. This study provides good evidence supporting that reconnection alone may not be able to trigger eruption; rather, MHD instability plays a more important role.
语种	英语
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/6940]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	Zou, Peng,Jiang, Chaowei,Feng, Xueshang,et al. A Two-step Magnetic Reconnection in a Confined X-class Flare in Solar Active Region 12673[J]. ASTROPHYSICAL JOURNAL,2019,870(2):97.
APA	Zou, Peng,Jiang, Chaowei,Feng, Xueshang,Zuo, Pingbing,Wang, Yi,&Wei, Fengsi.(2019).A Two-step Magnetic Reconnection in a Confined X-class Flare in Solar Active Region 12673.ASTROPHYSICAL JOURNAL,870(2),97.
MLA	Zou, Peng,et al."A Two-step Magnetic Reconnection in a Confined X-class Flare in Solar Active Region 12673".ASTROPHYSICAL JOURNAL 870.2(2019):97.