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Magnetic fields play a key role in most astrophysical systems, from the Sun to active galactic nuclei. They can be studied through their effects on atomic energy levels, which produce polarized spectral lines. In particular, anisotropic radiation 'pumping' processes (which send electrons to higher atomic levels) induce population imbalances that are(More)
Flares and X-ray jets on the Sun arise in active regions where magnetic flux emerges from the solar interior amd interacts with the ambient magnetic field. The interactions are believed to occur in electric current sheets separating regions of opposite magnetic polarity. The current sheets located in the corona or upper chromosphere have long been thought(More)
Aims. Study the contradictory magnetic field strength distributions retrieved from independent analyses of spectropolarimetric observations in the near-infrared (1.56 µm) and in the visible (630 nm) at internetwork regions. Methods. In order to solve this apparent controversy, we present simultaneous and co-spatial 1.56 µm and 630 nm observations of an(More)
Velocity oscillations in sunspot umbrae have been measured simultaneously in two spectral lines: the photospheric Silicon i 10827Å line and the chromo-spheric Helium i 10830Å multiplet. From the full Stokes inversion of temporal series of spectropolarimetric observations we retrieved, among other parameters, the line of sight velocity temporal variations at(More)
the date of receipt and acceptance should be inserted later Abstract. We investigate the fine structure of the sunspot penumbra by means of a model that allows for a flux tube in horizontal pressure balance with the magnetic background atmosphere in which it is embedded. We apply this model to spectropolarimetric observations of two neutral iron lines at(More)
Velocity oscillations " measured " simultaneously at the photosphere and the chromosphere-from time series of spectropolarimetric data in the 10830Å region-of different solar magnetic features allow us to study the properties of wave propagation as a function of the magnetic flux of the structure (i.e. two different-sized sunspots, a tiny pore and a facular(More)
We describe the presence of wave front dislocations in magnetohydrodynamic waves in stratified stellar atmospheres. Scalar dislocations such as edges and vortices can appear in Alfvén waves, as well as in general magnetoacoustic waves. We detect those dislocations in observations of magnetohydrodynamic waves in sunspots in the solar chromosphere. Through(More)
Theoretical modeling of propagation of magneto-acoustic waves in magnetic regions below sunspots. ABSTRACT We use 2D numerical simulations and eikonal approximation to study properties of magneto-acoustic gravity waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of(More)
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