Centaurus

Centaurus A (also known as NGC 5128 or Caldwell 77) is a prominent galaxy in the constellation of Centaurus. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type(lenticular galaxy or a giant elliptical galaxy)and distance (10-16 million light-years). NGC 5128 is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers.The galaxy is also the fifth brightest in the sky, making it an ideal amateur astronomy target,although the galaxy is only visible from low northern latitudes and the southern hemisphere.

The center of the galaxy contains a supermassive black hole weighing in at 55 million solar masses,which ejects a relativistic jet that is responsible for emissions in the X-ray and radio wavelengths. By taking radio observations of the jet separated by a decade, astronomers have determined that the inner parts of the jet are moving at about one half of the speed of light. X-rays are produced farther out as the jet collides with surrounding gases resulting in the creation of highly energetic particles. The radio jets of Centaurus A are over a million light years long.

Like other starburst galaxies, a collision is suspected to be responsible for the intense burst of star formation. Spitzer Space Telescope studies have confirmed that Centaurus A is colliding with and devouring a smaller spiral galaxy.