Back Reaction on the Photospheric Magnetic field in Solar
Eruptions Dandan Ye Slide 2 Contents Paper review: 2005 J.J. Sudol
and J.W. Harvey Longitudinal magnetic field changes accompanying
solar flares My work about flare-related magnetic field evolutions
to the X1.8 flare on 2012.10.23 Slide 3 Paper review Background:
Re-examined the basic assumptions of flare theories: the
photospheric magnetic field does not change significantly during
flares Data:15 X-class solar flares Global Oscillation Network
Group (GONG) magnetograms Slide 4 Paper review Slide 5 The time
variation of the magnetic field that occurs during a flare can be
characterized to first order with a step function.
(Sudol&Harvey 2004) a, b, c, n, and t 0 are the free parameters
Slide 6 Paper review 2003.11.2 X8.3 flare Time variation plots for
(10*10) pixels Slide 7 Paper review Left: magnetic field image of a
10-min average Middle: dB map Right: B vs t (representative points
for four hours) Slide 8 Paper review Slide 9 Comparison with flare
emission GONG & TRACE Slide 10 Paper review Discussion: Abrupt,
significant, and permanent changes of the photospheric longitudinal
magnetic field are ubiquitous features of X-class flares. Reasons:
unclear (like flows compress the field; parts of the field shift
horizontally; flux submerges out of sight..) Slide 11 Paper review
Many of the field changes with penumbrae and the recent
observations show that penumbrae weaken during flares Penumbral
magnetic field more vertical So, the field lines are pulled or
relax upward by the erupting flare. Slide 12 My work AR 11598
(close to the west limb) Line-of sight component of magnetic field
change Vector of magnetic field change Intensity Data Slide 13 My
work Data: Helioseismic and Magnetic Imager(HMI) data on board the
SDO LOS: Magnetogram with a spatial resolution of ~1'' and a
cadence of 45 seconds Vector: Vector magnetic field with a spatial
resolution of ~1'' and a cadence of 12 min. Intensity: Continuum
data with a cadence of 45 seconds Slide 14 My work Intensity Slide
15 My work Intensity Dif_image 10.23 3:24-3:12 Slide 16 My work
Transformation of field vectors Bh represents the components of B
in the directions parallel to the photosphere Br is the radial
field component Slide 17 My work Slide 18 Vector Slide 19 My work
Slide 20 LOS Dif_image 10.23 3:30-3:00 Slide 21 My work LOS Slide
22 My work LOS Slide 23 My work LOS Slide 24 My work LOS Slide 25
My work Summary: 1. Obviously the X1.8 flare produces abrupt and
significant magnetic field structure change in intensity, vector
field and LOS. 2. For this X1.8 flare, the diskward flux would
decrease and the limbward flux would increase. Slide 26 My work
Slide 27 3. Prove the speculation in Wang & Liu (2010): Field
lines changing to more vertical state when the central region
pressure is released after flares. 4. Prove the speculation in
Sudol & Harvey (2005). Slide 28 Thanks!
