Centaurus A
Centaurus A or NGC 5128 is a prominent galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop at his home in New South Wales, Australia.
NGC 5128 is either a Hubble type lenticular galaxy or a elliptical galaxy. It is 1016 million light-years away.
NGC 5128 is one of the closest radio galaxies to Earth. Its active center has been well studied. The galaxy is the fifth brightest in the sky, and is an ideal amateur astronomy target. The galaxy is only visible from low northern latitudes and the southern hemisphere.
Spitzer Space Telescope studies have confirmed that Centaurus A is colliding with, and devouring, a smaller spiral galaxy. Like other starburst galaxies, the collision produced the intense burst of star formation.
The center of the galaxy has a supermassive black hole. Its mass is about 55 million solar masses. This ejects a relativistic jet with emissions in the X-ray and radio wavelengths. Astronomers have taken radio observations of the jet ten years apart. They found that the inner parts of the jet are moving at about half the speed of light. X-rays are produced further out as the jet collides with surrounding gas. This produces highly energetic particles. The radio jets of Centaurus A are over a million light years long.
References
Starburst galaxies