Magnetic Non-Potentiality of Solar Active Regions and Peak X-Ray Flux of the Associated Flares

Abstract

Predicting the severity of the solar eruptive phenomena like flares and Coronal Mass Ejections (CMEs) remains a great challenge despite concerted efforts for several decades. The advent of high quality vector magnetograms obtained from Hinode (SOT/SP) has increased the possibility of meeting this challenge. In particular, the Spatially Averaged Signed Shear Angle (SASSA) seems to be an unique parameter to quantify the non-potentiality of the active regions. We demonstrate the usefulness of SASSA for predicting the flare severity. For this purpose we present case studies of the evolution of magnetic non-potentiality using 115 vector magnetograms of four active regions namely ARs NOAA 10930, 10960, 10961 and 10963 during December 08-15, 2006, June 03-10, 2007, June 28-July 5, 2007 and July 10-17, 2007 respectively. The NOAA ARs 10930 and 10960 were very active and produced X and M class flares respectively, along with many smaller X-ray flares. On the other hand, the NOAA ARs 10961 and 10963 were relatively less active and produced only very small (mostly A and B-class) flares. For this study we have used a large number of high resolution vector magnetograms obtained from Hinode (SOT/SP). The analysis shows that the peak X-ray flux of the most intense solar flare emanating from the active regions depends on the magnitude of the SASSA at the time of the flare. This finding of the existence of a lower limit of SASSA for a given class of X-ray flare will be very useful for space weather forecasting. We have also studied another non-potentiality parameter called mean weighted shear angle (MWSA) of the vector magnetograms along with SASSA. We find that the MWSA does not show such distinction as the SASSA for upper limits of GOES X-Ray flux of solar flares, however both the quantities show similar trends during the evolution of all active regions studied.

25 pages, 5 figures, accepted for publication in the Astrophysical Journal

References in corpus (4)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• Effect of Polarimetric Noise on the Estimation of Twist and Magnetic Energy of Force-Free Fields
• Magnetic Tension of Sunspot Fine Structures

Cited by in corpus (10)

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• On the Force-Freeness of the Photospheric Sunspot Magnetic Fields as Observed from Hinode (SOT/SP)
• Multiwavelength study of a Solar Eruption from AR NOAA 11112 I. Flux Emergence, Sunspot Rotation and Triggering of a Solar Flare
• Impulsive energy release and non-thermal emission in a confined M4.0 flare triggered by rapidly evolving magnetic structures
• Global Energetics of Solar Flares. XI. Flare Magnitude Predictions of the GOES-Class
• On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158
• Are the photospheric sunspots magnetically force-free in nature?
• Helicity of the solar magnetic field