Starburst
NGC 253's most notable feature is the mentioned starburst that is taking place of it and that has created several super star clusters on NGC 253's center discovered with the aid of the Hubble Space Telescope: one with a mass of 1,5*106 solar masses, and absolute magnitude of at least -15 and two others with 5*104 solar masses and absolute magnitudes around -11; later studies have discovered an even more massive cluster heavily obscured by NGC 253's interstellar dust with a mass of 1,4*107 solar masses, an age of around 5,7*106 years, and rich in Wolf-Rayet stars.
Star formation is also high in the northeast of NGC 253's disk, where a number of red supergiant stars can be found, and on its halo are present young stars as well as some amounts of neutral hydrogen. This, along other peculiarities found on NGC 253, suggest a gas-rich dwarf galaxy collided with it 200 million years ago, disturbing its disk and starting the present starburst.
Read more about this topic: Sculptor Galaxy