TURBULENT MAGNETIC-FIELDS IN THE SOLAR PHOTOSPHERE - DIAGNOSTICS AND INTERPRETATION
被引:0
作者:
FAUROBERTSCHOLL, M
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h-index: 0
机构:OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
FAUROBERTSCHOLL, M
FEAUTRIER, N
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h-index: 0
机构:OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
FEAUTRIER, N
MACHEFERT, F
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h-index: 0
机构:OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
MACHEFERT, F
PETROVAY, K
论文数: 0引用数: 0
h-index: 0
机构:OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
PETROVAY, K
SPIELFIEDEL, A
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h-index: 0
机构:OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
SPIELFIEDEL, A
机构:
[1] OBSERV PARIS, DAMAP, F-92195 MEUDON, FRANCE
[2] EOTVOS LORAND UNIV, DEPT ASTRON, H-1083 BUDAPEST, HUNGARY
来源:
ASTRONOMY & ASTROPHYSICS
|
1995年
/
298卷
/
01期
关键词:
MHD;
MAGNETIC FIELDS;
SUN;
MAGNETIC FIELD SUN;
PHOTOSPHERE;
TURBULENCE;
D O I:
暂无
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
Turbulent magnetic fields in the solar photosphere may be determined by their depolarizing Hanle effect on the linear polarization of some solar absorption lines formed outside active regions (Stenflo 1982). In Faurobert-Scholl (1993) the center-to-limb variation of the linear polarization in the Sri 4607 Angstrom line was analyzed. It was shown that it is affected by the Hanle effect due to a weak magnetic field with mixed polarity at small scales. The accurate determination of the turbulent magnetic field strength requires radiative transfer calculations taking into account the effect of collisions and magnetic fields on the frequency and angular redistribution of the light. Here we present the different steps in the theory of redistribution, together with the first precise quantum calculations of the collisional cross-sections between hydrogen and Sri and CaI atoms. These new results are then used to perform a more accurate determination of the turbulent magnetic field strength in the solar photosphere. It is shown that the center-to-limb variation of the linear polarization in the Sri line is mainly sensitive to the average value of the field strength between the altitudes 200 and 400 km. According to the observations this average value is between 20 and 10 G. A theoretical interpretation is given in terms of a one-dimensional passive magnetic field transport equilibrium model with first-order smoothing. The resulting [\B-x\](z) equilibrium distribution reproduces the observations rather well, but the uncertainty in the amplitude, height-dependence and interpretation of microturbulence suggests that the present model could be brought to an even better agreement with the observations if a microturbulence different from the VAL3C model is used. It is finally pointed out that in the upper photosphere the turbulent field becomes force-free instead of being passively transported. It is found that this does not seriously modify our conclusions.