X-Rays from the Galactic Plane
In February 2000, the orbiting
Chandra X-ray Observatory spent 27 hours
staring into the plane
of our Milky Way galaxy.
Its target was a spot in the small
constellation
Scutum, within the Milky Way's
zone of avoidance where galactic
gas and dust clouds block visible light, making a poor
window for optical telescopes.
However the penetrating x-ray observations looked through
the obscurations revealing the Milky Way and the Universe beyond.
The x-ray view is
reconstructed above in false color.
Distant active galaxies
emitting high energy x-rays appear as blue dots,
while reddish dots are sources of lower energy x-rays,
likely stars within the
Milky Way itself.
Intriguing is the
diffuse blue glow of high energy x-rays,
distinct from the individual sources in the picture.
Astronomers have
long debated whether our galactic plane's apparently
extended x-ray emission
was due to discrete sources or diffuse hot gas.
As these results
suggest diffuse interstellar
gas with a temperature of tens of millions of degrees Celsius
is indeed the answer, other questions arise.
What heats the gas to these incredible temperatures?
Why does this energetic gas linger in the galactic plane?