The Sculptor Galaxy, also known as the Silver Coin or Silver Dollar Galaxy, NGC 253, is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.

NGC 253's most notable feature is the earlier-mentioned starburst which is taking place within it, and which 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 in its halo there are young stars as well as some amounts of neutral hydrogen. This, along with other peculiarities found in NGC 253, suggest that a gas-rich dwarf galaxy collided with it 200 million years ago, disturbing its disk and starting the present starburst.



As happens in other galaxies suffering strong star formation such as Messier 82, NGC 4631, or NGC 4666, the stellar winds of the massive stars produced in the starburst as well as their deaths as supernovae have blown out material to NGC 253's halo, in the form of a superwind that seems to be inhibiting star formation in the galaxy.



Although supernovae are generally associated with starburst galaxies, only one supernova has been detected within the Sculptor Galaxy.The supernova, named SN 1940E, is located approximately 54″ southwest of the galaxy's nucleus. It was discovered in November 1940.



Central black hole



Recent research suggests the presence in the center of this galaxy of a supermassive black hole, with a mass estimated to be 5 million times that of our Sun



Recent distance estimates



At least two techniques have been used to measure distances to Sculptor in the past ten years.



Using the planetary nebula luminosity function method, an estimate of 10.89 +0.85

−1.24 Mly* (3.34 +0.26

−0.38 Mpc*) was achieved in 2006.



Sculptor is close enough that the tip of the red giant branch (TRGB) method may also be used to estimate its distance. The estimated distance to Sculptor using this technique in 2004 yielded 12.8 ± 1.2 Mly (3.94 ± 0.37 Mpc).



A weighted average of the most reliable distance estimates gives a distance of 11.4 ± 0.7 Mly (3.5 ± 0.2 Mpc).