Turbulence, fractals, and the solar granulation.
Abstract
The authors give a brief, mostly qualitative introduction into the topics of convection and turbulence, and their description, mainly referring to laboratory experiments. Following Mandelbrot (1967), the concept of the fractal dimension is introduced and some earlier results of measurements of the fractal dimension in laboratory tubulence are discussed. The authors address the question whether hints of turbulence have been observed in the solar photosphere, and describe three independent methods of determining the fractal dimension of the solar granulation: the area-perimenter relation, the line and the plane intersection method. An analysis of a set of high resolution granulation photographs taken with the balloon-borne "Spectro-Stratoskop" telescope yields a fractal dimension of d ≈ 1.9 for granules of diameters >1.32 arcsec and of d ≈ 1.3 for smaller granules, analysing the area-perimeter relation of approx. 40000 granules.
- Publication:
-
Applying Fractals in Astronomy
- Pub Date:
- 1991
- Bibcode:
- 1991afa..conf...77B