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January 2003
Supergranulation: Not bubbling but waving
The surface of the Sun is perpetually in motion as a result of a variety of influences. One level of patterning is called supergranulation, a network of features on the scale of 30,000 km. For many years supergranulation has been assumed to be caused by bubbles of convected matter emerging at the solar surface, but there has been little evidence to support this. Now Doppler velocity images from the SOHO spacecraft show that supergranulation exhibits wave-like behaviour, undergoing oscillations with periods of 6–9 days. This points to a mechanism involving travelling wave convection in a highly turbulent fluid.
Wave-like properties of solar supergranulation
L. GIZON, T. L. DUVALL JR & J. SCHOU
Nature
421, 43–44 (2003); doi:10.1038/nature01287
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