Observation of Turbulence in Solar Surface Convection: I. Line Parameter Correlations |
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Authors: | A Hanslmeier A Kučera J Rybák H Wöhl |
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Institution: | 1.Institut für Physik, Geophysik Astrophysik Meteorologie,Graz,Austria;2.Astronomical Institute, Slovak Academy of Sciences,Tatranská Lomnica,Slovakia;3.Kiepenheuer-Institut für Sonnenphysik,Freiburg,Germany |
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Abstract: | By using slit observations of solar photospheric lines shifted by 0.4 arcsec, a 2D field on the Sun was scanned to obtain
a 16-minute time series of 2D line-parameter variations. The aim was to investigate in detail the occurrence of turbulence
that can be measured by line-width variations extracted from the line profiles. The continuum-intensity variation served as
a proxy for granular (bright) and intergranular (dark) areas. The results show that turbulence is not limited to the intergranular
space but is also produced by horizontal motions that may become supersonic, leading to turbulence. These motions lead to
brightenings, as predicted by theoretical models. Thus, enhanced line-width variations are found to occur in both bright and
dark areas. A Sobel filter served to detect the areas where strong gradients in the line parameters occur. By applying this
filter to the different line-parameter variations over the 2D field observed, we can determine whether there exists a similarity
of these strong-gradient patterns with other parameters that characterize granular motions such as intensity variations or
velocity fluctuations. |
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Keywords: | Sun: granulation Sun: photosphere Turbulent convection |
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