Magnetic Helicity of Solar Active Regions as Revealed by Vector Magnetograms and Coronal X-Ray Images

	Magnetic Helicity of Solar Active Regions as Revealed by Vector Magnetograms and Coronal X-Ray Images
	Xu, Haiqing1,2 ; Gao, Yu1 ; Zhang, Hongqi1 ; Sakurai, Takashi 2; Hagino, Masaoki 2; Sokoloff, Dmitry 3; Pevtsov, Alexei A.4
刊名	PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
	2012-06-25
卷号	64 期号:3
关键词	Sun: corona Sun: magnetic fields Sun: sunspots
英文摘要	We have used photospheric vector magnetograms of 15 different solar active regions to calculate the current helicity parameter, alpha(av) and the linear force-free field (LFFF) parameter, alpha(best), that fits best the observed transverse field. The data were obtained with the Solar Magnetic Field Telescope at the Huairou Solar Observing Station, the National Astronomical Observatories of China, the Solar Flare Telescope of the National Astronomical Observatory of Japan, and the Haleakala Stokes Polarimeter at the Mees Solar Observatory, University of Hawaii, from 1997 to 2000. The agreement in sign of alpha(av) between three vector magnetographs is better than 90%. For alpha(best), the agreement is 80%-90%. The line-of-sight magnetograms observed with the Michelson Doppler Imager (MDI) on SOHO and coronal X-ray images observed with the Soft X-ray Telescope (SXT) on Yohkoh have been used to determine the constant alpha(c) of the LFFF in the corona. The value of alpha(c) corresponds to the extrapolated coronal field whose field lines best match, by visual inspection, the structure of coronal loops in X-ray images. It is found that the sign agreement between photospheric alpha(av) or alpha(best) and coronal alpha(c) is lower (60%-85%). We consider the differences in measurements, observing conditions, data reduction methods, and limitation in LFFF extrapolation, and discuss their contributions to the dispersions in the hemispheric sign rule of helicity.
收录类别	SCI
语种	英语
WOS记录号	WOS:000305868200012
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/6087]
专题	国家天文台_太阳物理研究部
作者单位	1.Chinese Acad Sci, Natl Astron Observ, Key Lab Solar Activ, Beijing 100012, Peoples R China 2.Natl Inst Nat Sci, Natl Astron Observ Japan, Mitaka, Tokyo 1818588, Japan 3.Moscow MV Lomonosov State Univ, Dept Phys, Moscow 119992, Russia 4.Natl Solar Observ, Sunspot, NM 88349 USA
推荐引用方式 GB/T 7714	Xu, Haiqing,Gao, Yu,Zhang, Hongqi,et al. Magnetic Helicity of Solar Active Regions as Revealed by Vector Magnetograms and Coronal X-Ray Images[J]. PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN,2012,64(3).
APA	Xu, Haiqing.,Gao, Yu.,Zhang, Hongqi.,Sakurai, Takashi.,Hagino, Masaoki.,...&Pevtsov, Alexei A..(2012).Magnetic Helicity of Solar Active Regions as Revealed by Vector Magnetograms and Coronal X-Ray Images.PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN,64(3).
MLA	Xu, Haiqing,et al."Magnetic Helicity of Solar Active Regions as Revealed by Vector Magnetograms and Coronal X-Ray Images".PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 64.3(2012).