The M81 Group is a galaxy group in the constellations Ursa Major and Camelopardalis that includes the galaxies Messier 81 and Messier 82, as well as several other galaxies with high apparent brightnesses. The approximate center of the group is located at a distance of 3.6 Mpc, making it one of the nearest groups to the Local Group. The group is estimated to have a total mass of ×1012M☉. The M81 Group, the Local Group, and other nearby groups all lie within the Virgo Supercluster.
NGC 6240, also known as the Starfish Galaxy, is a nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. The galaxy is the remnant of a merger between three smaller galaxies. The collision between the three progenitor galaxies has resulted in a single, larger galaxy with three distinct nuclei and a highly disturbed structure, including faint extensions and loops.
NGC 1, also occasionally referred to as GC 1, UGC 57, PGC 564 or Holm 2a is an intermediate spiral galaxy of the morphological type Sbc, located approximately 210 to 215 million light-years from the Solar System in the constellation Pegasus. It was discovered on 30 September 1861 by Heinrich d'Arrest.
The Antennae Galaxies are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation. They were discovered by William Herschel in 1785.
Interacting galaxies are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy disturbing the primary galaxy's spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.
NGC 7252 is a peculiar galaxy resulting from an interaction between two galaxies that started a billion years ago. It is located 220 million light years away in the constellation Aquarius. It is also called Atoms for Peace Galaxy, a nickname which comes from its loop-like structure, made of stars, that resembles a diagram of an electron orbiting an atomic nucleus.
Arp 87 is a pair of interacting galaxies, NGC 3808A and NGC 3808B. They are situated in the Leo constellation. NGC 3808A, the brighter, is a peculiar spiral galaxy, while NGC 3808B is an irregular galaxy.
Mayall's Object is the result of two colliding galaxies located 500 million light years away within the constellation of Ursa Major. It was discovered by American astronomer Nicholas U. Mayall of the Lick Observatory on 13 March 1940, using the Crossley reflector. When first discovered, Mayall's Object was described as a peculiar nebula, shaped like a question mark. Originally theorized to represent a galaxy reacting with the intergalactic medium, it is now thought to represent the collision of two galaxies, resulting in a new object consisting of a ring-shaped galaxy with a tail emerging from it. It is thought that the collision between the two galaxies created a shockwave that initially drew matter into the center which then formed the ring.
Arp 271 is a pair of similarly sized interacting spiral galaxies, NGC 5426 and NGC 5427, in the constellation of Virgo. It is not certain whether the galaxies are going to eventually collide or not. They will continue interacting for tens of millions of years, creating new stars as a result of the mutual gravitational attraction between the galaxies, a pull seen in the bridge of stars already connecting the two. Located about 130 million light-years away, the Arp 271 pair is about 130,000 light-years across. It was originally discovered in 1785 by William Herschel. It is speculated, that the Milky Way will undergo a similar collision in about five billion years with the neighbouring Andromeda Galaxy, which is currently located about 2.6 million light-years away.
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 7727 is a peculiar galaxy in the constellation Aquarius. It harbors two galactic nuclei, each containing a supermassive black hole, separated 1,600 light years apart.
NGC 2276 is an intermediate spiral galaxy in the constellation Cepheus. The galaxy lies 120 million light-years away from Earth. NGC 2276 has an asymmetrical appearance, most likely caused by gravitational interactions with its neighbor, elliptical galaxy NGC 2300. One of the many starburst spiral arms contains an intermediate mass black hole with 50,000 times the mass of the Sun, named NGC 2276-3c. NGC 2276-3c has produced two jets: a large-scale radio jet, approximately 2,000 light years long, and an "inner jet" about 6 light years long. The galaxy shows an enhanced rate of star formation that may have been triggered by a collision with a dwarf galaxy, or by the gravitational interaction with its neighbor compressing gas and dust.
NGC 3610 is an elliptical galaxy in the constellation Ursa Major. It was discovered on 8 April 1793 by William Herschel.
NGC 1741 is a distant pair of interacting galaxies in the Eridanus constellation. It was discovered on 6 January 1878 by French astronomer Édouard Stephan. As a result of the collision, the galaxies are in a rapid starbust phase. The galaxies are classed as Wolf–Rayet galaxies due to their high content of rare Wolf–Rayet stars.
NGC 4647 is an intermediate spiral galaxy estimated to be around 63 million light-years away in the constellation of Virgo. It was discovered by astronomer William Herschel on March 15, 1784. NGC 4647 is listed along with Messier 60 as being part of a pair of galaxies called Arp 116; their designation in Halton Arp's Atlas of Peculiar Galaxies. The galaxy is located on the outskirts of the Virgo Cluster.
PGC 44691 is a spiral galaxy located about 350 million light-years away in the constellation Coma Berenices. It belongs to a galaxy cluster known as the Coma Cluster. In 1994, the Hubble Space Telescope observed PGC 44691 and the nearby elliptical galaxy NGC 4881 to infer the distance to the Coma Cluster.
NGC 806 is a spiral galaxy approximately 166 million light-years away from Earth in the constellation Cetus. It was discovered by American astronomer Lewis A. Swift on November 1, 1886 with the 16" refractor at Warner Observatory.
NGC 6040 is a spiral galaxy located about 550 million light-years away in the constellation Hercules. NGC 6040 was discovered by astronomer Édouard Stephan on June 27, 1870. NGC 6040 is interacting with the lenticular galaxy PGC 56942. As a result of this interaction, NGC 6040's southern spiral arm has been warped in the direction toward PGC 56942. NGC 6040 and PGC 56942 are both members of the Hercules Cluster.
NGC 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of circa 230 million light years from Earth, which, given its apparent dimensions, means that NGC 541 is about 130,000 light years across. It was discovered by Heinrich d'Arrest on October 30, 1864. It is a member of the Abell 194 galaxy cluster and is included in the Atlas of Peculiar Galaxies in the category galaxies with nearby fragments. NGC 541 is a radio galaxy of Fanaroff-Riley class I, also known as 3C 40A.
