Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)
Markarian 231 (also designated UGC 8058) is an ultraluminous infrared galaxy, located about 600 million light-years away from Earth. It has long tidal tails and a disturbed shape, and a powerful quasar in the centre.
Its infrared luminosity is similar to that of quasars, making it one of the most luminous and powerful known ultraluminous infrared galaxies. Although the emission of many ultraluminous infrared galaxies appears to be dominated by energetic starbursts, Markarian 231 has been repeatedly identified as an exception and many pieces of evidence point toward an accreting supermassive black hole as the major power source behind the enormous infrared luminosity.
Although the primary power source behind the incredible far-infrared luminosity of Markarian 231 is almost certainly an active nucleus, the galaxy is also undergoing an energetic starburst. Most dramatically a nuclear ring of active star formation with a rate estimated to be greater than 100 solar masses per year has been found in the centre.