News from the world of maths

Plasma astrophysicists at the University of Warwick have found that key information about the Sun's "storm season" is being broadcast across the solar system in a fractal snapshot imprinted in the solar wind. This research opens up new ways of looking at both space weather and the unstable behaviour that affects the operation of fusion powered power plants.

Solar wind consists of a stream of plasma, mainly protons and electrons, that are ejected by the Sun's corona. On its way out the wind interacts with the Sun's magnetic field, broadcasting it across the universe. The researchers, led by Sandra Chapman, measured the strength of the magnetic field in the solar wind. They found that when the Sun is at the peak of its 11-year cycle, the graph they were plotting turned into a fractal. At this point the solar corona was at its most active, stormy and complex, due to sunspot activity, solar flares, etc. When the corona was quieter no fractal patterns were found in the solar wind.

This new information will help astrophysicists understand how the solar corona heats the solar wind and the nature of the turbulence of the solar wind with its implications for cosmic ray flux and space weather.

The techniques used to find and understand the fractal patterns in the solar wind are also being used to assist the quest for fusion power. Researchers in the University of Warwick's Centre for Fusion, Space and Astrophysics (CFSA) are collaborating with scientists from the EURATOM/UKAEA fusion research programme to measure and understand fluctuations in the world leading fusion experiment MAST (the Mega Amp Spherical Tokamak) at Culham. Controlling plasma fluctuations in tokamaks is important for getting the best performance out of future fusion power plants.

Find out more about fractals in Plus, and read more about fractal solar winds in New Scientist.

The geometry that gives rise to rainbows may help scientists to find out whether other planets contain water, which is necessary to sustain life. Rainbows are formed because light rays are bent, or refracted, and scattered as they enter droplets of liquid that hang in the atmosphere. The refraction occurs because light waves are slowed as they enter the droplet — think of a shopping trolley slowing down as you push it onto a lawn at an angle, and changing its direction as a result. The amount by which the light rays are slowed, and hence bent, depends on the liquid's consistency and is measured by its refractive index. Thus, different liquids give rise to rainbows at different angles, a fact that enabled researchers to determine that the clouds of Venus are droplets of concentrated sulfuric acid. Researchers now suggest that the same approach could be used to detect clouds made of liquid water in a planet's atmosphere.

Read more on the ABC News in science website, and find out more about refraction on Plus.