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HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24
Hao, Juan; Zhang, Mei
2011-06-01
Source PublicationASTROPHYSICAL JOURNAL LETTERS
Volume733Issue:2
AbstractUsing vector magnetograms obtained with the Spectro-polarimeter (SP) on board Hinode satellite, we studied two helicity parameters (local twist and current helicity) of 64 active regions that occurred in the descending phase of solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives the following results. (1) The 34 active regions of the solar cycle 24 follow the so-called hemispheric helicity rule, whereas the 30 active regions of the solar cycle 23 do not. (2) When combining all 64 active regions as one sample, they follow the hemispheric helicity sign rule as in most other observations. (3) Despite the so-far most accurate measurement of vector magnetic field given by SP/Hinode, the rule is still weak with large scatters. (4) The data show evidence of different helicity signs between strong and weak fields, confirming previous result from a large sample of ground-based observations. (5) With two example sunspots we show that the helicity parameters change sign from the inner umbra to the outer penumbra, where the sign of penumbra agrees with the sign of the active region as a whole. From these results, we speculate that both the Sigma-effect (turbulent convection) and the dynamo have contributed in the generation of helicity, whereas in both cases turbulence in the convection zone has played a significant role.
KeywordMagnetic Fields Sun: Activity Sunspots
DOI10.1088/2041-8205/733/2/L27
Indexed BySCI
Language英语
WOS IDWOS:000293135000011
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/7834
Collection太阳物理研究部
AffiliationChinese Acad Sci, Key Lab Solar Act, Natl Astron Observ, Beijing 100012, Peoples R China
Recommended Citation
GB/T 7714
Hao, Juan,Zhang, Mei. HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24[J]. ASTROPHYSICAL JOURNAL LETTERS,2011,733(2).
APA Hao, Juan,&Zhang, Mei.(2011).HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24.ASTROPHYSICAL JOURNAL LETTERS,733(2).
MLA Hao, Juan,et al."HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24".ASTROPHYSICAL JOURNAL LETTERS 733.2(2011).
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