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Fine Structure inside Flare Ribbons and its Temporal
EvolutionASAI Ayumi 1,
Masuda S. 2, Yokoyama T. 3, Shimojo M. 3, Kurokawa H. 1,Shibata,
K. 1, Ishii T. T. 1, Isobe H. 1, Takasaki H. 1, Kitai R. 1, Yaji K.
41: Kwasan Observatory, 2: STE lab., 3: Nobeyama Radio Obsevatory,
4: Kawabe Cosmic Park
January 22, 2002, Yohkoh 10th Anniv. Meeting
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Foot Point of Flare LoopNon-thermal particles bombard the
chromospheric plasma at both the foot points simultaneously. The
temporal evolution of both the foot points is very similar.(Sakao
1994)?simultaneously brightenFrom the site of highly-correlated
pair of foot points and the time of precipitation, the site and the
time of particle acceleration can be determined.
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Foot Point of Flare LoopPrecipitations of particles cause HXR
sources and Ha kernels.
HXR sources and Ha kernels show high correlation in their
locations and their temporal evolutions.(Kitahara & Kurokawa
1990)
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Foot Point of Flare LoopHXRHa images enable us to investigate
precipitation of non-thermal particles into the chromosphere with
higher spatial resolution than HXR and/or microwave.(Kurokawa
1988)HaSoft X-ray
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Todays Topic We determine precisely the site of precipitations
using the Ha data of the 2001 April 10 flare.
We compare the spatial distribution of the HXT sources with the
Ha kernels and discuss the energy release at the HXT sources.
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ObservationFlare 05:10 UT April 10, 2001GOES X2.3 classNOAA
9415
DataHaKwasan Observatory, Sartorius TelescopeEUVTRACE (171
image)magnetogramSOHO / MDIhard-X rayYohkoh / HXTmicrowaveNobeyama
RadioheliographHa image taken with FMT at Hida Obs.NOAA 9415
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Ha Movie of the FlareGreat Two-Ribbon Flare
Thanks to short exposure time, fine structure inside the flare
ribbons is clearly seen.
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Method of Data Analysis
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Method of Data Analysis Using cross-correlation functions of the
light curves, we identified the conjugate foot points in each
mesh.
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TRACE Flare LoopTRACE 171images show post-flare loops of 1MK
plasma.
The TRACE flare loops really connect the pairs.
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Time of BrighteningThe pairs are classified according to the
times of brightening.
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Temporal Evolution of Ha KernelsMovement of the site of energy
release.t
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Summary (1)We have invented a unique method for analyzing Ha
data.
We have investigated the site of the precipitation of particles
with higher spatial resolution.
We have followed the history of the energy release.
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HXT SourcesHXT sourcescontour lines : magnetic fieldPositive /
Negative
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Magnetic Field StrengthHa kernels without HXT sources : 300550
G
HXT sources : 12001350 G( 3 times larger)E1 : 300E2 : 1350E3 :
550E4 : 500W1 : 300W2 : 1200W3 : 500W4 : 450Magnetic Field Strength
(G)E4E3E1W4W3W1
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Magnetic Field Strength and Energy Release Rate3 times larger
magnetic field strength causes 27 times larger energy release rate
at the HXT sources than those of the other Ha kernels.
It is larger than the HXT dynamic range.Estimation of energy
release rate at each sourcevi : inflow velocityA : area of
reconnection pointIHXT dE/dt
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Summary (2)
We have found the differences of the magnetic field strengths
between the HXT sources and the other Ha kernels. Those at the HXT
sources are about 3 times larger than at the other Ha kernels.
Using Ha data, we have been able to investigate the weaker
brightenings where less energy release occur and cannot be seen in
HXT.
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Magnetic Field Strength and Energy Release RateEnergy release
rate of the HXT sources is 16-27 times larger than the energy
release rate of the other Ha kernels.Estimation of energy release
rate at each sourcevi : inflow velocityA : area of reconnection
pointa = 0.5 (Sweet-Parker)1 (Petschek)
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Light Curves of the FlareLight curves of the flare
The Ha light curve of the flares also shows gradual rise like
the SXR (GOES) light curve.
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Light Curve of Ha Kernels Light curves of each Ha kernels show
impulsive spikes like those of nonthermal radiation.
Each Ha kernel are generated by precipitation of nonthermal
particles.
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Time of Brightening
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Magnetic Field Strength and Nonthermal RadiationMeasure the
magnetic field strength along the outer sides of flare ribbons.
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Magnetic Field StrengthE3E1E2E4W3W2W1W4Ha kernels without HXT
sources : 400500 G
HXT sources : 12001400 G( 3 times larger)HXT sourceHXT
source+-