Prominances
are regions where magnetic field lines have broken high above the surface,
and charged particles are spiralling along them.
Where
the solar magnetic field lines are kinked and break through the surface
to form sunspots, a great deal of activity occurs. The magnetic energy
stored in the field can be released suddenly, heating the surrounding gas
to millions of degrees. This gas emits X-rays, gamma rays, and radio emission
and is called a solar flare.
Prominances
are regions where magnetic field lines have broken high above the surface,
and charged particles are spiralling along them.
All this activity can affect the solar
corona, the tenuous hot gas surrounding the Sun.
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The corona is extremely hot (millions of degrees), so
that the thermal velocities of particles exceeds the escape velocity of
the Sun. These particles (ions and electrons) stream away from the Sun,
following open magnetic field lines and form the
solar wind. The solar wind is very
tenuous (a few particles per cubic centimeters near the Earth)
and fast (about 500 km/s). This solar
wind continuously sweeps through the solar system, and is stronger during
periods of solar maximum.
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