Torsional oscillations of sunspots: magnetic and velocity fields observations
نویسندگان
چکیده
منابع مشابه
Torsional Oscillations of Relativistic Stars with Dipole Magnetic Fields
We present the formalism and numerical results for torsional oscillations of relativistic stars endowed with a strong dipole magnetic field, assumed to be confined to the crust. In our approach, we focus on axisymmetric modes and neglect higher-order couplings induced by the magnetic field. We do a systematic search of parameter space by computing torsional mode frequencies for various values o...
متن کاملTorsional Oscillations of Relativistic Stars with Dipole Magnetic Fields II. Global Alfvén Modes
We investigate torsional Alfvén modes of relativistic stars with a global dipole magnetic field. It has been noted recently (Glampedakis et al. 2006) that such oscillation modes could serve as as an alternative explanation (in contrast to torsional crustal modes) for the SGR phenomenon, if the magnetic field is not confined to the crust. We compute global Alfvén modes for a representative sampl...
متن کاملOscillations and running waves observed in sunspots
In order to study umbral oscillations, running penumbral waves and the relationship between them, we analyzed CCD, high resolution, sunspot observations obtained at center and the wings of the Hα line and the Fe I 5576 Å line. The UBF filter was used in order to produce high cadence sequences of filtergrams. Images were processed to remove the sharp intensity gradient between the umbra and the ...
متن کاملMagnetic Structure of Sunspots
In this review we give an overview about the current state-of-knowledge of the magnetic field in sunspots from an observational point of view. We start by offering a brief description of tools that are most commonly employed to infer the magnetic field in the solar atmosphere with emphasis in the photosphere of sunspots. We then address separately the global and local magnetic structure of suns...
متن کاملTorsional Magnetic Oscillations in Type I X-ray Bursts
Thermonuclear burning on the surface of a neutron star causes the expansion of a thin outer layer of the star, ∆R(t). The layer rotates slower than the star due to angular momentum conservation. The shear between the star and the layer acts to twist the star’s dipole magnetic field giving at first a trailing spiral field. The twist of the field acts in turn to ‘torque up’ the layer increasing i...
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ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2004
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s1743921304005770