ASAI Ayumi Kwasan Observatory, Kyoto University July 12, 2002 @Nobeyama Evolution of Flare Ribbons and Energy Release
Jan 05, 2016
ASAI Ayumi Kwasan Observatory, Kyoto University
July 12, 2002 @Nobeyama
Evolution of Flare Ribbons and Energy Release
“re”-connection of magnetic field line
Released energy by reconnection or induced energy into th
e region↑
Estimate by using physical values at t
he footpoints
Model of Magnetic Reconnection
Energy Release RatedE/dt depends on m
agnetic field B and inflow velocity vi
Assumingvi ⇒ vfoot
Bcorona ⇒ Bphotosphe
Examine the relation of these values with energy
release rate
32
4BAv
B
dt
dEi
Reconnection model indicates
A : area of the reconnection region
Energy Release Rate
Energy Release Rate
32
4BAv
B
dt
dEi
Reconnection model indicates
A : area of the reconnection region
Energy Release Rate
Time profile of HXR intensity is well fitted wi
th that of dE/dt
Flare・ 05:10 UT April 10, 2001・ GOES X2.3 class・ NOAA 9415
DataH ・・ Kwasan Observatory, Sartorius Telescopemagnetogram ・・ SOHO / MDIhard-X ray ・・ Yohkoh / HXTmicrowave ・・ Nobeyama Radioheliograph
Observation
H image taken with FMT at Hida Obs.
NOAA 9415
Sartorius Telescope
H Movie of the Flare
East West
Great Two-Ribbon Flare
Thanks to short exposure time,
fine structure inside the flare ribbons is
clearly seen.
E4
E3E2
E1
W4
W3 W2
W1HXR sources
HXR Sources
contour lines : magnetic fieldPositive / Negative
E2
W2
Measure the magnetic field strength along the outer sides of flare ribbons.
North
South
SOHO/MDI
Magnetic Field Strength and HXR Radiation
Magnetic Field Strength
E3E1
E2
E4
W3
W2
W1 W4
HXT source
HXT source
+
-
North South
North
South
positive
negative
Magnetic Field Strength
・ H kernels without HXT sources
: 300 ~ 550 G
・ HXT sources : 1200 ~ 1350 G
( ~ 3 times larger)
E1 : 300E2 : 1350E3 : 550E4 : 500
W1 : 300W2 : 1200W3 : 500W4 : 450
Magnetic Field Strength (G)
E4
E3
E1
W4
W3E2W2W1
E2W2
32
4BAv
B
dt
dEi
↓
Energy release rate of the HXR sources is 16-27 times larger than the energy release rate of
the other H kernels. It is larger than the HXT
dynamic range.
Estimation of energy release rate at each source
vi : inflow velocityA : area of reconnection point
32
4BAv
B
dt
dEi
vi : inflow velocity B∝
2+
= 0.5 (Sweet-Parker)
1 (Petschek)
magnetic field strength is 3 times larger
Magnetic Field Strength and Energy Release Rate
Evolution of Flare Ribbon
To examine separation of ribbons, we estimated the distance of the fronts of the ribbons from neutral line in the direction perpendicular to neutral line.
05:10
05:40
××
WestEastt
r r
Separation of Flare Ribbons
HXR sources appear when separation speed of flare ribbons slow down
×
WestEast
dis
tan
ce
fro
m n
eu
tral
lin
e
time time
Separation speed and HXR Sources
32
4BAv
B
dt
dEi
Slowing down of the ribbon-separation is caused by increase of magnetic field strength.
Both B and vi must be considered simultaneously Reconnection Rate and/or Poynting Flux
HXR sources appear when separation speed of flare ribbons slow down→inverse dependence!?
Separation Speed and Energy Release Rate
32
4BAv
B
dt
dEi
•Reconnection rate
Bcoronavi = Bphotospherevfoot
•Poynting Flux
Bcorona2vi ∝ Bphotosphere
2vfoot
Reconnection Rate and Poynting Flux
Reconnection Rate and Poynting Flux
Bphotosphere
Separating Speed
Distance from NL
B2×v
B×v
Microwave
HXR
Reconnection Rate and Poynting Flux
Summary (1)
The magnetic field strengths at the HXR sources are about 3 times larger than at the other H kernels.
This suggests that the energy release rate at the HXR sources is 16-27 times larger than those of the other H kernels.
32
4BAv
B
dt
dEi
3
2
4BAv
B
dt
dEi
2+
Summary (2)
The HXR sources appear when the separating speed of the flare ribbons are slowing down.
This seems to be inversely dependence on the energy release rate.
Summary (3)
There are good correlations between the energy release rate and the reconnection rate and poynting flux.