Beck, C.
Referencia bibliográfica
Solar Physics, Volume 264, Issue 1, pp.57-70
Fecha de publicación:
6
2010
Revista
Número de citas
2
Número de citas referidas
2
Descripción
I report observations of unusually strong photospheric and chromospheric
velocity oscillations in and near the leading sunspot of NOAA 10781 on 3
July 2005. I investigate an impinging wave as a possible origin of the
velocity pattern and the changes of the wave after the passage through
the magnetic fields of the sunspot. The wave pattern found consists of a
wave with about 3 Mm apparent wavelength, which propagates towards the
sunspot. This wave seems to trigger oscillations inside the
sunspot’s umbra, which originate from a location inside the
penumbra on the side of the impinging wave. The wavelength decreases and
the velocity amplitude increases by an order of magnitude in the
chromospheric layers inside the sunspot. On the side of the sunspot
opposite to the impinging plane wave, circular wave fronts centered on
the umbra are seen propagating away from the sunspot outside its outer
white-light boundary. They lead to a peculiar ring structure around the
sunspot, which is visible in both velocity and intensity maps. The fact
that only weak photospheric velocity oscillations are seen in the umbra
- contrary to the chromosphere where they peak - highlights the
necessity to include the upper solar atmosphere in calculations of wave
propagation through spatially and vertically extended magnetic field
concentrations such as sunspots.
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