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EUV filaments in 3D
from magnetic extrapolations toward stereoscopic observations
G. Aulanier & B. SchmiederObservatoire de Paris, LESIA
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Disc observations of EUV filaments Disc observations of EUV filaments
Observed only for < 912 A (Chiuderi Drago et al. 2001)
EUV lines EUV lines absorbedabsorbed in the Lyman in the Lyman continuum of Hydrogencontinuum of Hydrogen
912 = 60-100 H (Heinzel et al. 2001, Schmieder et al., 2002)
fewer materialfewer material can absorb the can absorb the background EUV radiationbackground EUV radiation
EUV shows EUV shows more massmore mass than H than H
°
(Heinzel et al. 2001)
SoHO/CDS
THEMIS/MSDP
distribution of cool material ? magnetic topology ? 3D is missing extra mass loading of CMEs ?
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3D magnetic field extrapolation 3D magnetic field extrapolation for one observed filament for one observed filament
Joint THEMIS/SoHO campaign, 05/05/2000 (conducted at MEDOC)
08:12 UT07:52 UT
located at E17 S21
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linear magneto-hydrostatic method linear magneto-hydrostatic method
+
+
-
-
x B = B + e-z/H Bz x uz (Low 1992)
= j (force free) + j (p;g)
Lower boundary : -/2 < x;y < /2 ; periodic
- Bz (z = 0) = B// (MDIdeproj) /cos
- = observed quasi-periodicity in x
- y axis = filament axis
Upper boundary : 0 < z < z arbitrary
lim B (z +) = 0
Departure from the force free approximation
(; H) cannot be fixed grid of 35 LMHS models
8Filament axis
05/05/00, 08:00 UT, SoHO/MDI magnetogram
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Selection of the best LMHS modelSelection of the best LMHS model
For each 3D model, compute & plot magnetic dips :
Compare dips with H observations only:
dipped field line
d = Hg = 300 km
- Locus of dips :
- Portion visible in H:
- dips to be matched with :
- Physical parameters :res = 0.94 ; = 3.08 x 10-8 m-1
H = 25 Mm
filament curved body & elbow
(Aulanier et al. 1999)
z
(B . ) B > 0Bz = 0
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LMHS model of the HLMHS model of the H filament filament
Calculation of dips on a 64 3 mesh :
2100 dips for z = ] 4 ; 96 ] 3500 dips for z = [ 0 ; 4 ]
H filament body + feet = Sheet of dips in high altitude flux tube + Side dips on the edge of photospheric parasitic polarities
(Aulanier & Démoulin 1998)
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LMHS model of the EUV filamentLMHS model of the EUV filament
Plot onto the EUV image the SAME dips from the SAME model built so as to match the H filament :
2100 dips for z = ] 4 ; 96 ] 3500 dips for z = [ 0 ; 4 ]
Magnetic dips computed up to :
dLyman = 1700 km
(calculated with approximated RT)
For hydrostatic-isothermal dips :
M (each dip) ~ 1.5 x M (H
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Magnetic topology of filament channelsMagnetic topology of filament channels
Filament body :magnetic dips in weakly twisted
(0.6 turns) and discontinuous flux tube
H & EUV extensions :low-lying dips due to parasitic polarities
located near the footpoints of somelong overlaying sheared loops
Magnetic loops
filament flux tube
overlaying arcades
Magnetic dips
z > 4 Mm
z < 4 Mm
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Estimate for the mass loading of CMEsEstimate for the mass loading of CMEs
Wide EUV feet
H feet
Overlaying arcades
Filament flux tube
CME front & cavity
Not ejected
M (each dip) ~ 1.5 x M (observable in H
unchanged
fall down to chromosphere
M (CME core) x 1.5
MOST of the mass
observed in EUV filament channels
will NOT be loaded into CMEs
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Toward STEREO observationsToward STEREO observationsEUV filament channels
=optically thick enough
stereo reconstruction
SECCHI / EUVI
3D structure & evolution
of EUV channels
SoHO/CDS FOV
05/05/00, 08:12 UT, SoHO/CDS, OV
SoHO/CDS FOV
same shape as observed in the 4 EIT wavelengths
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Magnetic loops
filament flux tube
overlaying arcades
Magnetic dips
z > 4 Mm
z < 4 Mm
Compare LMHS model Compare LMHS model with observed transit on the discwith observed transit on the disc
Several projections of one model :LMHS extrapolation of the 05/05/00, 8:00 UT, SoHO/MDI magnetogram