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Grahamshortuk
2010-Jun-08, 03:13 PM
I heard something on AstroCast today that made me remember something I heard a while ago.
Are sun spots flat on the surface of the sun? I seem to remember hearing that it had been detected that they were "dimples" or depressions in the surface; - is that correct?
http://www.oneminuteastronomer.com/wp-content/uploads/2009/09/Sunspot-group_l.jpg
They sure do look like a whirlpool, which would be cool to think about. :think:

Jeff Root
2010-Jun-08, 07:15 PM
It would certainly make sense that they would be somewhat
depressed below the level of the surrounding photosphere.
The yellow granules you can see in that image are columns
of hot gas rising at their centers, cooling, and then falling at
the brown edges. Each granule is about the area of Texas
and Oklahoma combined, on average. The granules are
raised up at the center and lower at the edges.

-- Jeff, in Minneapolis

Grahamshortuk
2010-Jun-08, 11:22 PM
Does it seem to you that, looking at various different close ups, that the surrounding plumes appear to be either sucked into a vortex, or spiraling out of one? Are there any good videos of these that show the motion?

George
2010-Jun-08, 11:47 PM
In 1774, Alexander Wilson (and Maskelyne) discovered that sunsports are embedded in the photosphere. This dimple-like appearance that becomes prominent when the spots are near the limbs is known as the Wilson Effect.

There is a fair drawing of the effect in this paper (http://articles.adsabs.harvard.edu//full/1967PASJ...19..220S/0000221.000.html).