Time evolution of coronal magnetic helicity in the flaring active region NOAA 10930

Sung Hong Park, Jongchul Chae, Ju Jing, Changyi Tan, Haimin Wang

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38 Scopus citations


To study the three-dimensional (3D) magnetic field topology and its long-term evolution associated with the X3.4 flare of 2006 December 13, we investigate the coronal relative magnetic helicity in the flaring active region (AR) NOAA 10930 during the time period of December 8-14. The coronal helicity is calculated based on the 3D nonlinear force-free magnetic fields reconstructed by the weighted optimization method of Wiegelmann, and is compared with the amount of helicity injected through the photospheric surface of the AR. The helicity injection is determined from the magnetic helicity flux density proposed by Pariat et al. using Solar and Heliospheric Observatory/Michelson Doppler Imager magnetograms. The major findings of this study are the following. (1) The time profile of the coronal helicity shows a good correlation with that of the helicity accumulation by injection through the surface. (2) The coronal helicity of the AR is estimated to be-4.3 × 1043 Mx2 just before the X3.4 flare. (3) This flare is preceded not only by a large increase of negative helicity,-3.2 × 1043 Mx2, in the corona over ∼1.5 days but also by noticeable injections of positive helicity through the photospheric surface around the flaring magnetic polarity inversion line during the time period of the channel structure development. We conjecture that the occurrence of the X3.4 flare is involved with the positive helicity injection into an existing system of negative helicity.

Original languageEnglish (US)
Pages (from-to)1102-1107
Number of pages6
JournalAstrophysical Journal
Issue number2
StatePublished - Sep 10 2010

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Sun: corona
  • Sun: flares
  • Sun: magnetic topology
  • Sun: photosphere


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