WAVES AND THE SUN
Electromagnetic radiation
The Sun emits, not just visible light, but light from all across the
electromagnetic spectrum - from radio waves to gamma-rays.
Sound waves
Sound waves can travel through all media: air, walls, and even the
Earth itself (earthquakes).
The speed with which the waves travel is the sound speed, and it
depends on both the temperature and density of the medium in which it
travels.
Sound waves are extemely important on the Sun as welll
Helioseismology
Seismology is the study of earthquakes and is done by measuring the
vibrations of the Earth's surface. Helioseismology is a comparatively
new field of science (begun in the 1970s) whereby vibrations of the
Sun's surface are measured.
The vibrations are measured from the light emitted
by the Sun's surface, and the problem has certain similarities to that
of standing waves in a string
As you go closer to the Sun's center the sound speed increases as
T1/2. Any wave that is going from the surface to
the center is forced to curve and eventually head back towards the
surface.
As the wave is confined by two boundaries, standing waves are set up
By making a model of the Sun, one can predict what sort of vibrations
are expected, which can then be compared with what is measured.