The conservation of magnetic flux demands a magnetic field fine structure as small as 15 km to explain the net circular polarization observed in penumbrae...
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PublicationSpectral signature of uncombed penumbral magnetic fields. Comment
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PublicationSpectral signature of uncombed penumbral magnetic fields. Reply
A combination of two penumbral models similar to those used by Martínez Pillet (2000) is presented. One matches the observed rms fluctuations perfectly while...
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PublicationSpectrograph distortion in sunspot line profiles
The way in which the effect of the instrumental polarization of a spectrograph can distort the shape of the intensity profiles in sunspots is shown empirically...
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PublicationSpectropolarimetric Investigation of the Propagation of Magnetoacoustic Waves and Shock Formation in Sunspot Atmospheres
Velocity oscillations in sunspot umbrae have been measured simultaneously in two spectral lines: the photospheric Si I λ10827 line and the chromospheric He I...
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PublicationSpectropolarimetry in a sunspot penumbra. Spatial dependence of Stokes asymmetries in Fe I 1564.8 nm
Stokes profiles of sunspot penumbrae show distinct asymmetries, which point to gradients in the velocity field and in the magnetic field. We present...
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PublicationSpectropolarimetry of a Decaying Sunspot Penumbra
We report on high angular resolution, high-precision spectropolarimetric measurements of a decaying sunspot. The spot gradually lost its penumbra during the...
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PublicationSpectroscopic determination of intensities of umbral bright features and adjacent background
Profiles of the Na I D doublet in three bright features (clusters of umbral dots), located in a relatively dark umbra, were analyzed by means of the 'local two...
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PublicationSpiral-shaped wavefronts in a sunspot umbra
Context. Solar active regions show a wide variety of oscillatory phenomena. The presence of the magnetic field leads to the appearance of several wave modes...
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PublicationStability of sunspots to convective motions. I - Adiabatic instability
For determining the adiabatic stability of a uniform vertical field in an arbitrary stratification it is sufficient to consider the limit of infinitesimal...