Abstract
Good quality photographs of many regular sunspots were obtained in three spectral regions, with the use of narrow band filters. Isodensity contours were used for measurements of the umbra and penumbra size along different axes of sunspots. A parameter based on the morphology of the whole sunspot was defined for a better study of the Wilson effect. Some interesting results are the following: (a) an east-west asymmetry of the Wilson effect was clearly observed, (b) differences in the phenomenon in the three spectral regions were barely significant compared with observational errors and (c) measurements indicate that larger sunspots have greater depth.
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Prokakis, T. The depth of sunspots. Sol Phys 35, 105–110 (1974). https://doi.org/10.1007/BF00156960
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DOI: https://doi.org/10.1007/BF00156960