view out of the themis telescope dome (tenerife) solar ... surface...the photosphere: a strongly...
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Solar Surface Anisotropy effecton the Magnetic Field
Véronique BommierLESIA, Observatoire de Paris
IAU Symposium 305Punta Leona (Costa Rica), 30 November-5 December 2014
view out of the THEMIS telescope dome (Tenerife)
VECTOR MAGNETIC FIELD MAPS
2 lines: Fe I 6301.5 and 6302.5 Å
independent ME inversion(UNNOFIT code, Bommier et al. 2007)
lines of the same multiplet: constant ΔH(simulation quiet Sun & AR by Khomenko & Collados 2007)
formation depth difference: 98 km
ambiguity removed by |divB|+|Jz| minimization(DIVB2, modified ME0 code of Leka et al., simulated annealing)
119 maps available96 THEMIS 2010-2013 campaigns & 23 HINODE
http://lesia.obspm.fr/perso/veronique-bommierVéronique Bommier's homepage
NOAA 10953Hinode 1 May 2007
vector current density
vector Lorentz force
Fe I 6301.5 Å and 6302.5 Åare 2 lines of the same multiplet 816
parallelism
from Khomenko, E., & Collados, M., 2007, ApJ 659, 1726
Direct measurement of ∆h by phase shift method (cross-spectral analysis):quiet Sun, HINODE data: ∆h = 63.2 ± 0.9 km (Faurobert et al., 2009, A&A 507, L29)
confirmed by 3D simulations of solar magneto-convection: ∆h = 69 kmStein & Nordlund's + Uitenbroek's codes (Grec et al., 2009, A&A 514, A91)
THEMIS observationof a
double sunspot (δ-spot)on 13 September 2005
MULTILINEdivB divB scaled by the aspect ratio
plot ofBX X BY Y BZ Z
plot of10BX X 10BY Y BZ Z
color scale: scaled to the measurement inaccuracy level (including inversion)
vertical gradient dBz/dz: 3 G/km horizontal gradient dBx/dx+dBy/dy: 0.3 G/km• Westendorp Plaza et al., 2001, ApJ 547, 1130
2 lines Fe I 6301.5 & 6302.5 Å observed with ASP (Sac Peak)SIR inversion, provides also d/dzresult: 1.5-2 G/km (4 G/km in a previous analysis)
• Balthasar & Schmidt, 1993, A&A 279, 2433 lines Fe I 6302.5 & 6842.7 Å & Fe II 6149.2 Åspectropolarimetry with the VTT (Izaña, Tenerife)inversion by comparison with theoretical profiles
by Grossmann-Doerth et al. (1988), G-D (1994)Unno-Rachkovsky sol. in a model atmosphere
d/dz is derivedresult: 2.5 to 3 G/km
• Pahlke & Wiehr, 1990, A&A 228, 2466 lines Si I 6142.9, Zr I 6143.2, Fe II 6149.2,
Ti I 6149.7, Fe I 6151.6, Na I 6154.2 Åcircular polarization observed with the Gregory-Coudé telescope (Tenerife)direct field measurement in umbra by Zeeman splittingbest agreement between the 6 lines if
a gradient of 2 G/km is assumed.
• Bruls, Solanki, Rutten & Carlsson, 1995, A&A 293, 225reanalyze FTS (Kitt Peak) observations by
Hewagama et al. (1993)2 infrared lines Mg I 12.22 & 12.32 m
(formed in the upper photosphere)MULTI code (non-LTE multilevel, Carlsson 1986)+ DELO Stokes profile synthesis
(Rees et al., 1989, Murphy, 1990, Murphy & Rees, 1990)result: 2-3 G/km
• Balthasar, 2006, A&A 449, 11693 lines Fe I 15648, 15452 & 10896 Åobserved with the TIP mounted on the VTT (Tenerife)8 sunspotsSIR inversionresult: 0.5 G/km
• Hagyard et al., 1983, Sol. Phys. 84, 131 highly sensitive line Fe I 5250.2 ÅMSFC magnetograph (Hunstville, Alabama)1 sunspotresult: 0.1-0.3 G/km
• suppose a regular sunspot diameter 10,000 kmsuppose that Bx varies from –1500 G to + 1500 Gfrom one penumbra side to the other penumbra sidethe mean horizontal gradient results into 0.3 G/km
• Eibe, Aulanier, Faurobert, Mein, Malherbe, 2002, A&A 381, 290, report a factor of 10 between
• observations: longitudinal field Na I D1 observed with THEMIS/MSDPdepth probing along the highly resolved line profile via response functions computed with the MULTI code(Carlsson 1986)
• theory: force-free extrapolation (Démoulin, Bagala, Mandrini, Hénoux, Rovira, 1997, A&A 325, 305)
• Pizzo, 1986, ApJ 302, 785magnetostatic equilibrium modelling (not force-free)result: 0.2-0.4 G/km (Fig. 15, for large tube radii
that model sunspots)
models
This cannot be ascribed to the lack of resolutionDemonstration in the spatial Fourier space
real space Fourier transform spatial Fourier space
f (x) f̂ (kx ) eikxx f (x)d xderivation:
xf (x) multiplication: kx f̂ (kx )
filtering: convolution product normal product
F(x) (x x ) f ( x )d x F̂(kx ) ̂(kx ) f̂ (kx )
What is measured: H or B ? I
What is measured: H or B ? II
Anisotropic Debye shielding(local dynamo)
Open Access paper by Bommier in Physics Research International http://www.hindawi.com/journals/physri/2013/195403/
+ Bommier, 2014, Comptes Rendus Physique, 15, 430 (available from the ADS)
The photosphere: a strongly stratified mediumviscosity-affected
From Brethouwer, Billant, Lindborg, Chomaz, J. of Fluid Mechanics, 585, 343:
The horizontal Froude number in the photosphere is found Fh 0.02 1 the photosphere is a strongly stratified medium (not the solar Corona, having Fh 3)The Reynolds number is Re 500 1, but the buoyancy Reynolds number is Rb ReFh
2 0.1 1 the photosphere lies in the "viscosity-affected flow regime": no inertial cascade can develop
the typical horizontal/vertical length ratio ("aspect ratio") is Re 20
the horizontal/vertical velocities and then Debye lengths are different: anisotropy
Temporary conclusion
An experimental proof ?
Physical conditions of the experiment taken fromVan Compernolle, Bortnik, Pribyl, Gekelman, et al., 2014,Phys. Rev. Letters 112, 145006
Description of the experiment in Gekelman et al., 1991, Rev. Sci. Instrum. 62, 2875
NOAA 10808 observed on 13 September 2005 with THEMIS
THEMIS
NOAA 10808 observed on 13 September 2005 with THEMIS
magnetic field vector
THEMIS
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