The relaxation of sheared magnetic fields: A contracting process | |
Ji, Haisheng![]() | |
刊名 | ASTROPHYSICAL JOURNAL
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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. |
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