منابع مشابه
Coronal potential magnetic fields from photospheric sources with finite width
Finite width photospheric sources are used to generate coronal potential magnetic field configurations. The prescription of a suitable distribution of the magnetic flux function within such regions allows to solve the Grad-Shafranov equation and, using the superposition principle, to obtain magnetic field configurations related to arbitrary combinations of photospheric sources and sinks. Follow...
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Aims. The origin and evolution of the magnetic helicity in the solar corona are not well understood. For instance, the magnetic helicity of an active region is often about 1042 Mx2 (1026 Wb2), but the observed processes whereby it is thought to be injected into the corona do not yet provide an accurate estimate of the resulting magnetic helicity budget or time evolution. The variation in magnet...
متن کاملStrength distribution of solar magnetic fields in photospheric quiet Sun regions
Context. The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed Mn i line at 553.7 nm, allows such differentiation. Aims. To analyse the distr...
متن کاملOn the Force-Freeness of Photospheric Magnetic Fields in Solar Active Regions: The Current Density Method
We introduce and apply a method to investigate the force-free character of the photospheric magnetic fields in solar active regions. The vertical current density, inferred from vector magnetograms, is decomposed into a helical (assumed field-aligned) component, and a component perpendicular to the magnetic field. Contrary to the classical method of calculating the integrated Lorentz forces, the...
متن کاملVertical Lorentz Force and Cross-field Currents in the Photospheric Magnetic Fields of Solar Active Regions
We demonstrate that the vertical Lorentz force and a corresponding lower limit of the cross-field electric current density can be calculated from vector magnetograms of solar active regions obtained at a single height in the solar atmosphere, provided that the vertical gradient of the magnetic field strength is known at this height. We use a predicted vertical magnetic field gradient derived fr...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1958
ISSN: 0074-1809
DOI: 10.1017/s0074180900237820