威尔逊效应

尽管表面的凹陷可以用威尔逊效应广泛的解释，Bray和Loughhead (1965)指称威尔逊效应的真正解释在于黑子物质相对于光球层的透明度。他们在其著作的书中第93至99页说明他们的想法。C.H. Tong在2005年也提出了类似的解释。

太阳黑子是密集的磁场阻碍了对流热能传递的结果，太阳黑子比光球层的其他部分冷，有效的温度大约是4,000°C (大约7,000°F)。 海因利希·史瓦贝在19世纪发现太阳黑子的数量有着大约11年的太阳周期。

In astronomy, the Wilson effect is the perceived depression of a sunspot's umbra, or center, in the Sun's photosphere. The magnitude of the depression for the umbra is between 500 and 1000 km, with an average of 600 km.

Sunspots result from the blockage of convective heat transport by intense magnetic fields. Sunspots are cooler than the rest of the photosphere, with effective temperatures of about 4,000°C (about 7,000°F). Sunspot occurrence follows an approximately 11-year period known as the solar cycle, discovered by Heinrich Schwabe in the 19th century.

History

In 1769, during solar cycle 2, Scottish astronomer Alexander Wilson, working at the Macfarlane Observatory, noticed that the shape of sunspots noticeably flattened as they approached the Sun's limb due to solar rotation.

These observations were published in 1774 and showed that sunspots were features on the solar surface, as opposed to minor planets or objects above it. Moreover, he observed what is now termed the Wilson effect: the penumbra and umbra vary in the manner expected by perspective effects if the umbrae of the spots are in fact slight depressions in the surface of the photosphere.

Alternative interpretations

While the surface-depression interpretation of the Wilson effect is widespread, Bray and Loughhead contended that "the true explanation of the Wilson effect lies in the higher transparency of the spot material compared to the photosphere". A similar interpretation was expressed by C.H. Tong.