A statistical study of the geometrical Wilson effect

✍ Scribed by M. Collados; J. C. Toro Iniesta; M. Vazquez

• Book ID: 104642477
• Publisher: Springer
• Year: 1987
• Tongue: English
• Weight: 554 KB
• Volume: 112
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00148782

✦ Synopsis

An analysis has been carried out of the centre-to-limb variation of the apparent sizes of the umbra, penumbra and whole spot. It has revealed that the umbral size decreases with height. We have interpreted this result in terms of the penumbral geometrical height scale. A value of 230 km, which is larger than that of the photosphere or the umbra, explains the observed decrease. An intrinsic asymmetry in the penumbra of old sunspots has also been found, the western penumbra being slightly shorter that the rest of the penumbra. This explains why the inverse Wilson effect is present, preferentially, in the western hemisphere, as found in previous investigations. A comparison with other works is also made.