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Magnetic Helicity Transport in Active Region NOAA 10930. Zhang, Y., Tan, B. L., Yan, Y. H Solar radio research group National Astronomical Observatories Chinese Academy of Sciences. Magnetic Helicity. Rotational motion of sunspot around its center.
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Magnetic Helicity Transport in Active Region NOAA 10930 Zhang, Y., Tan, B. L., Yan, Y. H Solar radio research group National Astronomical Observatories Chinese Academy of Sciences
Magnetic Helicity Rotational motion of sunspot around its center Rotational motion of sunspot of its center Shear motion Helical structure in filament or CME
Magnetic helicity can be transported from the sub-photosphere into solar coronal through photosphere 1. Emergence of helical field lines 2. Twisted of exist field lines (Zhang et al. 2008; Min & Chae, 2009;Kazachenko et al. 2009) 3. Shear motion (Yang et al,2004; Liu & Zhang, 2006)
Magnetic helicity transport in AR 10486 Helicity accumulation Rotational motion –3.0×1043 Mx2 LCTmethod –5.2×1043 Mx2 Helicity accumulation before CMEs Oct 28 X17.2Oct 29 X10.0 –1.5×1043 Mx2 –1.0×1043 Mx2 (rotational motion) –2.7×1043 Mx2 –1.3×1043 Mx2 (LCTmethod) Zhang, Y., et al., 2008, Solar Physics, 247, 39
Rotational motion Flux emergence Motivation: to check which process is the most important in magnetic helicity transport Berger & Field, 1984; Pevtsov, Maleev & Longcope, 2003, Zhang, Liu & Zhang,2008 In this condition, shear motion along neutral line does not include (Berger & Field , 1984; Chae, 2001; Chae et al., 2001; Nindos, Zhang & Zhang, 2003; Demoulin & Berger, 2003)
10930 Sample: NOAA 10930 12 09 S05E32 12 13 S05W33
f1 f2 12 09 12 10 12 11 12 12 12 13 Sample: NOAA 10930 Rotational speed, flux emergence rate, magnetic flux, the twist of the field lines
Radius of sunspot Radius of r_θ plot 1.3R 1.1R 360 0 r-θ plot
R=1.2 2006 12 13 2006 12 12 2006 12 11 2006 12 10 2006 12 09
Magnetic helicity transport by rotational motion and flux emergence △Hemergence = –6.0×1043 (Hinode) △Hrotation=–1.3×1043 (Hinode) △Hlct = –5.0×1042 Mx2 (MDI)
Discussion rotation speed normalized emergence rate This work is in progress.
Relationship between the magnetic helicity transport and the microwave burst: the profile of the rate of magnetic helicity transport is coincident with that of microwave emission flux. Our observations suggest that the transport of magnetic helicity plays a significant role in solar eruption. Zhang, Y., et al., 2008, ApJ, 682, L133