A starburst galaxy is one undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy or the star formation rate observed in most other galaxies. For example, the star formation rate of the Milky Way galaxy is approximately 3 M☉/yr, while starburst galaxies can experience star formation rates of 100 M☉/yr or more. In a starburst galaxy, the rate of star formation is so large that the galaxy will consume all of its gas reservoir, from which the stars are forming, on a timescale much shorter than the age of the galaxy. As such, the starburst nature of a galaxy is a phase, and one that typically occupies a brief period of a galaxy's evolution. The majority of starburst galaxies are in the midst of a merger or close encounter with another galaxy. Starburst galaxies include M82, NGC 4038/NGC 4039, and IC 10.
The Perseus cluster is a cluster of galaxies in the constellation Perseus. It has a recession speed of 5,366 km/s and a diameter of 863′. It is one of the most massive objects in the known universe, containing thousands of galaxies immersed in a vast cloud of multimillion-degree gas.
NGC 4571 is a spiral galaxy located in the constellation of Coma Berenices that William Herschel thought was Messier 91 in Charles Messier' catalog of deep-sky objects, before nearly two centuries later that object was determined to be the nearby barred spiral galaxy NGC 4548.
NGC 51 is a lenticular galaxy in the constellation Andromeda. It has a diameter of 90,000 light-years. The galaxy was discovered on September 7, 1885 by Lewis Swift, who described it as "Pretty faint, pretty small, round, brighter middle."
NGC 125 is a lenticular galaxy located in the constellation Pisces. It is designated as subclass Sa Ring in the galaxy morphological classification scheme. It lies approximately 235 million light-years away.
NGC 128 is a lenticular galaxy in the constellation Pisces. It is approximately 190 million light-years from the Sun and has a diameter of about 165,000 light-years.
NGC 142 is a spiral galaxy in the constellation of Cetus. It was discovered by Frank Muller in 1886.
NGC 237 is a spiral galaxy located in the constellation Cetus. It was discovered on September 27, 1867 by Truman Safford.
NGC 298 is a spiral galaxy in the constellation Cetus. It was discovered on September 27, 1864 by Albert Marth. NGC 298 is situated close to the celestial equator and, as such, it is at least partly visible from both hemispheres in certain times of the year. Given its B magnitude of 14.7, NGC 298 is visible with the help of a telescope having an aperture of 20 inches or more.
NGC 304 is a lenticular galaxy in the constellation Andromeda. It was discovered on October 23, 1878, by Édouard Stephan.
NGC 333 is a lenticular galaxy located approximately 755 million light years away in the constellation Cetus. It was discovered in 1877 by Wilhelm Tempel. It is recorded as NGC 333 in the New General Catalogue. It has a companion galaxy, named PGC 3073571, which is presumed to be a physical pair with NGC 333.
NGC 375 is an elliptical galaxy located in the constellation Pisces. It was discovered on September 12, 1784 by William Herschel. It was described by Dreyer as "pretty faint, small, round, brighter middle." Along with galaxies NGC 379, NGC 380, NGC 382, NGC 383, NGC 384, NGC 385, NGC 386, NGC 387 and NGC 388, NGC 375 forms a galaxy cluster called Arp 331.
NGC 3862 is an elliptical galaxy located 300 million light-years away in the constellation Leo. Discovered by astronomer William Herschel on April 27, 1785, NGC 3862 is an outlying member of the Leo Cluster.
NGC 493, also occasionally referred to as PGC 4979 or GC 281, is a barred spiral galaxy in the constellation Cetus. It is located approximately 90 million light-years from Earth and was discovered on December 20, 1786 by astronomer William Herschel. It was later also observed by his son, John Herschel. John Dreyer, creator of the New General Catalogue, described the galaxy as "very faint, large, much extended 60°" with "a little brighter middle".
NGC 3840 is a spiral galaxy located about 320 million light-years away in the constellation Leo. The galaxy was discovered by astronomer Heinrich d'Arrest on May 8, 1864. NGC 3840 is a member of the Leo Cluster. The galaxy is rich in neutral atomic hydrogen and is not interacting with its environment.
NGC 3844 is a lenticular galaxy located about 320 million light-years away in the constellation Leo. The galaxy was discovered by astronomer Heinrich d'Arrest on May 8, 1864. NGC 3844 is a member of the Leo Cluster and is likely to be a low-luminosity AGN (LLAGN).
NGC 3845 is a barred lenticular galaxy located about 270 million light-years away in the constellation Leo. NGC 3845 was discovered by astronomer John Herschel on March 17, 1831. It is a member of the Leo Cluster and is likely to be a low-luminosity AGN (LLAGN).
NGC 3883 is a large low surface brightness spiral galaxy located about 330 million light-years away in the constellation Leo. NGC 3883 has a prominent bulge but does not host an AGN. The galaxy also has flocculent spiral arms in its disk. It was discovered by astronomer William Herschel on April 13, 1785 and is a member of the Leo Cluster.
NGC 7130 is a spiral galaxy located in the constellation Piscis Austrinus. It is located at a distance of about 220 million light years from Earth, which, given its apparent dimensions, means that NGC 7130 is about 100,000 light years across. It was discovered by John Herschel on September 25, 1834, and discovered independently by Lewis Swift on September 17, 1897. The location of the galaxy given in the New General Catalogue was off by 30 arcminutes in declination from the location of the galaxy.
