Strongest source of cosmic radio wave s, lying in the direction of the constellation Sagittarius.
Discovered by Milky Way Galaxy . The region is relatively small and constitutes an intense source of infrared radiation thought to be emitted partly by stars and partly by dust around them. Within the region is a much smaller radio source, Sagittarius (Sgr) A*, which appears to mark the centre of the Galaxy. Observations indicate that the galactic nucleus contains a black hole with a mass of one million to several million times that of the Sun; they also provide a strong case that Sgr A* is the black hole. The activity at the Galaxy's centre resembles that of an active galactic nucleus but on a much smaller scale.