Helicity on the Sun: • What is it good for anyway? Slide 1 of 10830
Helicity has done extremely well from 1999-present (much better than my 401K!) Slide 2 of 10830
Kusano et al (2002) had studied helicity and energy flow into photosphere in AR8100, Nov. 2-5, 1997 • Helicity injection due to vertical flows, 6 x 1026 Wb2, comparable with helicity injection due to horizontal flows • Energy injected into corona due to helicity injection, 2 x 1025 J – larger than emitted by all flares during same period
Moon et al, 2008, NOAA 8100 • - Impulsive helicity injections episodes coinciding with C, M-class flares. • Both positive and negative helicity in injected by shear motions. • - The flare X-ray flux integrated over the X-ray emission time strongly correlates with the magnetic helicity injected during the flaring interval. Park et al 2008; 7 active regions - All major flares were preceded by a significant helicity accumulation, (1.8-16) x 1042 Mx2 over 0.5 to a few days. - average helicity change rate in the first phase shows strong correlation with the time-integrated soft X-ray flux • Park et al 2010; 378 ARs • (91 large ARs), difference in the magnetic helicity injection rate between flaring ARs and nonflaring ARsby a factor of 2 • - GOES C-flare-productive probability as a function of helicity injection displays a sharp boundary between flare-productive ARs and flare-quiet ones. Absolute value of the magnetic helicity induced by photospheric horizontal motions accumulated during the flaring time interval vs. the corresponding GOES X-ray flux integrated over the flaring time.
Reiner, et al. 2010 • NHGV (Normalized Helicity Gradient Variance) is effective at separating flaring and non-flaring active regions and even separates among C-, M-, and X-class flare producing regions. • It also provides advance notice of flare occurrence, as it increases 2–3 days before the flare occurs.
You might not need helicity for a flare, but it helps.