Observation of Turbulence in Solar Surface Convection: I. Line Parameter Correlations
Authors:
A. Hanslmeier, A. Kucera, J. Rybak, H. Wohl
Image & caption:
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Image caption::
Histograms of the line parameters continuum intensity, line width, Doppler velocity, and residual intensity derived from the Fe I 630.25 nm line. Continuum and residual intensity are normalized and the line width and the Doppler velocity are given in the physical units of miliangstrems and kilometers per second, respectively.
Description:
By using slit observations of solar photospheric lines 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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SAS
