Ker Than (of 3 Quarks Daily) in Space.com:
Astronomers have traced the source of mysterious high-energy X-rays and gamma rays in space to a little known star cluster in the Milky Way.
The cluster sits about 19,000 light-years away from Earth in the constellation Scutum. It contains about 20,000 stars, most of which are hot, young blue stars.supernovae.
Astronomers had known about the star cluster before, but it was only recently that they confirmed the number of stars it held.
In the late 1990’s, several observatories detected very high-energy X-rays and gamma rays coming from the region but astronomers were uncertain about their source. It was thought the blasts might have originated from distant galaxies or from pulsating stars known as pulsars, which typically emit radio waves but can send out other wavelengths of energy as well.
A team of researchers is now proposing that the blasts are the result of massive stars known as red supergiants in the cluster that exploded cataclysmically as
More here.