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NGC 5128, the radio galaxy Centaurus A

Date created: 2000-04-13

Tags: N/A

This unusual galaxy in Centaurus was first discovered by James Dunlop at the Parramatta Observatory near Sydney in 1826. The optical galaxy seen here is now known as NGC 5128, and is also the source of the powerful radio emission known as Centaurus A. It is a most unusual object, an elliptical galaxy crossed by a dust lane. Elliptical galaxies are usually almost featureless and mostly dust-free, while galaxies with pronounced dust lanes are usually spirals.

One of the nearer galaxies, NGC 5128 is about 10 million light years away, and host to the most powerful nearby radio source. It was one of the first radio galaxies discovered, by pioneering Australian radio astronomers in 1948, from a cliff-top near Sydney. This remarkable galaxy is also a copious source of X- and gamma rays as well as visible and infrared radiation. These are characteristics of an 'active' galaxy, one where the massive black hole present in most large galaxies is actively accreting material from its surroundings. This intense activity is probably the result of the merger of a dusty spiral with an elliptical galaxy, an explanation that accounts for the galaxy's optical appearance. This image here is about 15 arc minutes across, but the radio lobes of the galaxy extend out to 10 degrees or more.

Image was derived from an AAT plate taken in blue light.

Credit: David Malin

© Australian Astronomical Observatory