The relaxation of sheared magnetic fields: A contracting process

CORC > 紫金山天文台 > 中国科学院紫金山天文台 > 太阳活动的多波段观测研究团组

	The relaxation of sheared magnetic fields: A contracting process
	Ji, Haisheng; Huang, Guangli ; Wang, Haimin
刊名	ASTROPHYSICAL JOURNAL
	2007-05-01
卷号	660 期号:1 页码:893-900
关键词	sun : activity sun : flares
ISSN号	0004-637X
英文摘要	In recent years, several authors have reported a contracting motion for solar flaring loops. That is, during the rising phase of solar flares, hard X-ray (HXR) loop-top sources or radio/extreme-ultraviolet (EUV) flaring loops have a descending motion and, at the same time, H alpha ribbons or HXR footpoints (FPs) are converging. The usual expansion motion of flaring loops occurs only after the contraction. So far, the contracting motion cannot be fully explained in a two-dimensional flare model. The recent high-cadence H alpha observation of an M-class flare made by Ji et al. at GanYu Solar Station of Purple Mountain Observatory may provide a clue leading to a proper understanding. The observations show that the flare shear decreases steadily during both the contraction and expansion phases. In this paper, we provide supporting observational evidence by giving a detailed analysis of the M6.8-class flare of 2003 June 17. For this flare, the EUV flaring loops, H alpha ribbons, and HXR loop-top source show well-correlated contraction and subsequent expansion. The flare shear of this event, indicated by H alpha ribbons, HXR FPs, and EUV flaring loops, decreases steadily throughout. The observations apparently imply that the contracting motion of flaring loops may be the result of the relaxation of the sheared magnetic field. In the framework of sheared linear force-free arcades, we establish a quantitative model to show that the release of magnetic energy will reduce magnetic shear of the arcades and less sheared arcades will have smaller height and span.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	SOLAR-FLARES ; CURRENT SHEET ; RECONNECTION ; SHRINKAGE ; RHESSI ; ENERGY ; LOOPS ; MODEL ; PHASE
收录类别	SCI
语种	英语
WOS记录号	WOS:000246108700076
公开日期	2012-02-05
内容类型	期刊论文
源URL	[http://159.226.72.40/handle/332002/2470]
专题	紫金山天文台_太阳活动的多波段观测研究团组
作者单位	1.Purple Mt Observ, Nanjing 210008, Peoples R China 2.New Jersey Inst Technol, Big Bear Solar Observ, Big Bear City, CA 92314 USA
推荐引用方式 GB/T 7714	Ji, Haisheng,Huang, Guangli,Wang, Haimin. The relaxation of sheared magnetic fields: A contracting process[J]. ASTROPHYSICAL JOURNAL,2007,660(1):893-900.
APA	Ji, Haisheng,Huang, Guangli,&Wang, Haimin.(2007).The relaxation of sheared magnetic fields: A contracting process.ASTROPHYSICAL JOURNAL,660(1),893-900.
MLA	Ji, Haisheng,et al."The relaxation of sheared magnetic fields: A contracting process".ASTROPHYSICAL JOURNAL 660.1(2007):893-900.