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Unformatted text preview: SOLAR WIND We now know that the solar wind comprises a stream of particles from the Sun moving at speeds of 450km s-1 (slow stream) or 700 km s-1 (fast stream) more or less radially outwards. The high- speed wind originates from predominantly open field areas in coronal holes. The low-speed wind originates from the predominantly closed field areas near the equator. The solar wind has a variable temperature and composition. On average it has around 5 particles per cc (5 10-6 m-3 ), mainly electrons and protons, though there are some heavier ions. This is an almost completely dissociated plasma of effectively infinite conductivity, at a temperature of around 100,000K. It is known to get out to at least 100 AU, though at some point it must meet the interstellar medium at the heliopause and be randomised there. with solar flares/CMEs causing denser and faster outburst. The Ulysses spacecraft has been the first to fly sufficiently far outside the solar ecliptic to be able to confirm the presence of the solar...
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- Fall '10