view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly...

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Solar Surface Anisotropy effect on the Magnetic Field Véronique Bommier LESIA, Observatoire de Paris IAU Symposium 305 Punta Leona (Costa Rica), 30 November-5 December 2014 view out of the THEMIS telescope dome (Tenerife)

Transcript of view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly...

Page 1: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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)

Page 2: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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

Page 3: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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)

Page 4: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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)

Page 5: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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

Page 6: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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 )

Page 7: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

What is measured: H or B ? I

Page 8: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

What is measured: H or B ? II

Page 9: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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)

Page 10: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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

Page 11: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

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

Page 12: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

NOAA 10808 observed on 13 September 2005 with THEMIS

THEMIS

Page 13: view out of the THEMIS telescope dome (Tenerife) Solar ... Surface...The photosphere: a strongly stratified medium viscosity-affected From Brethouwer, Billant, Lindborg, Chom az, J.

NOAA 10808 observed on 13 September 2005 with THEMIS

magnetic field vector

THEMIS