A Peculiar Velocity Pattern in and near the Leading Sunspot of NOAA 10781: Wave Refraction by Large-Scale Magnetic Fields - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




A Peculiar Velocity Pattern in and near the Leading Sunspot of NOAA 10781: Wave Refraction by Large-Scale Magnetic Fields - Astrophysics > Solar and Stellar Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: I report observations of unusually strong photospheric and chromosphericvelocity oscillations in and near the leading sunspot of NOAA 10781 on 03 July2005. I investigate an impinging wave as a possible origin of the velocitypattern, and the changes of the wave after the passage through the magneticfields of the sunspot. The wave pattern found consists of a wave with about 3Mm apparent wavelength that propagates towards the sunspot. This wave seems totrigger oscillations inside the sunspot-s umbra, which originate from alocation inside the penumbra on the side of the impinging wave. The wavelengthdecreases and the velocity amplitude increases by an order of magnitude in thechromospheric layers inside the sunspot. On the side of the sunspot opposite tothe impinging plane wave, circular wave fronts centered on the umbra are seenpropagating away from the sunspot outside its outer white-light boundary. Theylead to a peculiar ring structure around the sunspot, which is visible in bothvelocity and intensity maps. The fact that only weak photospheric velocityoscillations are seen in the umbra - contrary to the chromosphere where theypeak there - highlights the necessity to include the upper solar atmosphere incalculations of wave propagation through spatially and vertically extendedmagnetic field concentrations like sunspots.



Autor: C. Beck

Fuente: https://arxiv.org/



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