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EUV filaments in 3D from magnetic extrapolations toward stereoscopic observations

EUV filaments in 3D from magnetic extrapolations toward stereoscopic observations. G. Aulanier & B. Schmieder Observatoire de Paris, LESIA. Disc observations of EUV filaments. SoHO/CDS. °. Observed only for l < 912 A (Chiuderi Drago et al. 2001)

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EUV filaments in 3D from magnetic extrapolations toward stereoscopic observations

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  1. EUV filaments in 3Dfrom magnetic extrapolations toward stereoscopic observations G. Aulanier & B. Schmieder Observatoire de Paris, LESIA

  2. Disc observations of EUV filaments SoHO/CDS ° • Observed only for l < 912 A (Chiuderi Drago et al. 2001) aEUV lines absorbed in the Lyman continuum of Hydrogen • t912 = 60-100 tHa (Heinzel et al. 2001, Schmieder et al., 2002) afewer material can absorb the background EUV radiation a EUV shows more mass than Ha THEMIS/MSDP (Heinzel et al. 2001) • distribution of cool material ? • magnetic topology ? 3D is missing • extra mass loading of CMEs ?

  3. 3D magnetic field extrapolation for one observed filament Joint THEMIS/SoHO campaign, 05/05/2000(conducted at MEDOC) 07:52 UT 08:12 UT located at E17 S21

  4. linear magneto-hydrostatic method • xB = aB + ze-z/HsBzxuz(Low 1992) = j (force free) + j (sp;g) Departure from the force free approximation • Lower boundary :-D/2 < x;y < D/2 ; periodic • -Bz (z = 0)=B// (MDIdeproj) /cosq • - D=observed quasi-periodicity in x • -y axis=filament axis • Upper boundary : 0 < z < Dzarbitrary • limB(z a +) = 0 h + Filament axis - + D - h 05/05/00, 08:00 UT, SoHO/MDI magnetogram 8 (a ;H) cannot be fixed a grid of 35 LMHS models

  5. Selection of the best LMHS model h For each 3D model, compute & plot magnetic dips : - Locus of dips : (B . s) B > 0 Bz = 0 z - Portion visible in Ha : dipped field line da = Hg = 300 km (Aulanier et al. 1999) h Compare dips with Ha observations only: - dips to be matched with : filament curved body & elbow a/ ares = 0.94 ; a = 3.08 x 10-8 m-1 - Physical parameters : H = 25 Mm

  6. LMHS model of the Ha filament h Calculation of dips on a 64 3 mesh : a2100 dips for z = ] 4 ; 96 ] a3500 dips for z = [ 0 ; 4 ] Ha filament body + feet = Sheet of dips in high altitude flux tube + Sidedips on the edge of photospheric parasitic polarities (Aulanier & Démoulin 1998)

  7. LMHS model of the EUV filament h Plot onto the EUV image the SAME dips from the SAME model built so as to match the Ha filament : a2100 dips for z = ] 4 ; 96 ] a3500 dips for z = [ 0 ; 4 ] h Magnetic dips computed up to : adLyman = 1700 km (calculated with approximated RT) h For hydrostatic-isothermal dips : aM (each dip) ~ 1.5 xM (Ha)

  8. Magnetic topology of filament channels Magnetic loops filament flux tube overlaying arcades Magnetic dips z > 4 Mm z < 4 Mm Filament body : magnetic dips in weakly twisted (0.6 turns) and discontinuous flux tube Ha & EUV extensions : low-lying dips due to parasitic polarities located near the footpoints of some long overlaying sheared loops

  9. Estimate for the mass loading of CMEs Overlaying arcades CME front & cavity Filament flux tube M (CME core) x 1.5 M (each dip) ~ 1.5 xM (observable in Ha) unchanged Not ejected fall down to chromosphere Ha feet MOST of the mass observed in EUV filament channels will NOT be loaded into CMEs Wide EUV feet

  10. Toward STEREO observations EUV filament channels = optically thick enough stereo reconstruction SECCHI / EUVI 3D structure & evolution of EUV channels same shape as observed in the 4 EIT wavelengths SoHO/CDS FOV SoHO/CDS FOV 05/05/00, 08:12 UT, SoHO/CDS, OV

  11. Compare LMHS model with observed transit on the disc Magnetic loops filament flux tube overlaying arcades Magnetic dips z > 4 Mm z < 4 Mm Several projections of one model : LMHS extrapolation of the 05/05/00, 8:00 UT, SoHO/MDI magnetogram

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