Explanation:
A journey to the center of a red giant star is very firmly in the
realm of science fiction.
But the science of
asteroseismology can explore the
conditions there.
The technique is to time the small variations in a star's
brightness measured by the
planet hunting Kepler spacecraft.
Regular variations indicate stellar oscillations, analogous to
sound waves,
that compress and
decompress the gas causing brightness changes.
As
recently discovered in red giant stars, some of the oscillations
detected have periods that would cause them to penetrate
to the stellar core.
In that extreme environment they actually become more
intense and can return to the surface.
These echoes from the red giant's core are illustrated in
this frame from a
computer generated animation.
Remarkably, the
periods measured
for the oscillations can even indicate how and where the
red giant star's energy production, by
hydrogen or helium fusion, is taking place.
APOD's status if the US government shuts down
