Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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MAGNETIC HELICITY OF SOLAR ACTIVE REGIONS AND ITS IMPLICATIONS

  • SAKURAI T. (National Astronomical Observatory) ;
  • HAGINO M. (School of Informatics, Meisei University)
  • Published : 2003.06.01
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Abstract

We have studied the magnetic helicity of active regions by using the data from (1) the photo-electric magnetograph of the Okayama Observatory (1983-1995) and (2) the video magnetograph of NAOJ/Mitaka (1992-2000). The latitude distribution of helicity showed a tendency that the regions in the north (south) hemisphere have negative (positive) helicities, respectively, which is already known as the hemispheric sign rule. If we look into the sign of helicity as a function of time, the sign rule was less definite or was reversed sometimes in the sunspot minimum phase. We also studied the relation between the magnetic helicity and the sunspot tilt angles, and found that these two quantities are positively correlated, which is opposite to the expectation of a theoretical model. The implications of this cycle-phase dependence of helicity signs and the correlation between magnetic he Ii city and sunspot tilt angles are discussed.

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References

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