"Three new types of object have been discovered in our galaxy: huge
gamma-ray clouds, dense X-ray engines almost hidden in cocoons of
dust, and bubbles blown by the wind from giant stars.

All three discoveries were reported on Monday at a conference at
Stanford University in California, US.

Two come courtesy of the High Energy Stereoscopic System (HESS), an
array of four telescopes in Namibia that detects photons of extremely
high energy. When one of these gamma rays hits the atmosphere, it
produces a flash of blue light that HESS can pick up.

HESS has seen such gamma rays coming from Westerlund 2, a cluster of
massive, bright stars about 25,000 light years away. The emission is
too diffuse to be coming directly from the stars. "The gamma-ray
source is much larger than the cluster itself," says team member Olaf
Reimer of Stanford."

Much more here http://space.newscientist.com/article.ns?id=dn11120