X-ray Binary Stars
X-ray Binaries (in yellow) near the Galactic Center
If human eyes could see X-rays rather than optical light, we
would see a very different sight when looking at the sky. We would be
overwhelmed by a few hundred very bright stars, mostly concentrated towards the center
of our galaxy.
Most of these stars would be X-ray binaries, where
a black hole
or neutron star
is devouring material from its companion star. Because humans do
not see naturally in the X-ray spectrum, we invented telescope
observatories to expand our vision capabilities, and to provide a
unique probe into how the universe
operates under extreme physical conditions.
X-ray binaries are a special class of binary stars. They are made
up of a normal star and a collapsed star (a white dwarf, neutron star,
or black hole).
These pairs of stars produce X-rays if the stars are in close enough
proximity that material is pulled off the normal star by the gravity of
the dense, collapsed star. The additional material
accreted onto the surface must go through a violent
transition region called the "boundary layer." In the boudary layer,
friction within the disk heats up the accreting
material to temperatures exceeding a million degrees, and forces the
material to spiral down gradually onto the
white dwarf surface. Scientists think the X-rays primarily
come from the boundary layer.
Tell me more about:
Mass exchange in Binary
Binaries that Pulse and
Determining Orbits and Masses
Last Modified: December 2010