Centaurus A is thought to have been formed by the merger of two galaxies. (European Southern Observatory )
After more than 50 hours of imaging at a variety of wavelengths, astronomers at the European Southern Observatory's La Silla Observatory in Chile have produced a spectacular new image of the galaxy Centaurus A, one of the most prominent radio-emitting sources in the universe.
Centaurus A, about 12 million light-years from Earth in the southern constellation Centaurus (the Centaur), was discovered in 1826 by British astronomer James Dunlop using the Parramatta observatory in Australia. Its radio emissions were not discovered until the 1950s, when the first radiotelescopes became available. Astronomers believe that the bright nucleus, strong radio emissions and jets streaming out from the galaxy are produced by a supermassive black hole, about 100 million times the mass of Earth's sun, at its center.
Centaurus A is an elliptical galaxy, and the glow that fills much of the image is produced by billions of older, cooler stars. But its shape is obscured by the broad and patchy band of dark material, which is composed of dust and young stars. The areas with a red glow are star-forming clouds of hydrogen. The features of the galaxy suggest that astronomers are observing the merger of two galaxies, with the dusty band representing the mangled remains of a spiral galaxy in the process of being ripped apart by the gravitational pull of the primary galaxy.
Extending from the galaxy to the upper left corner of the image are two groups of reddish filaments, which are roughly lined up with the huge jets that are prominent in radio images. Both sets are stellar nurseries containing hot young stars. The inner jet is about 35,000 light-years from the nucleus of the galaxy, while the outer one is about 65,000 light-years away.