The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10^6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.
A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.
NGC 4881 is an elliptical galaxy in the northern constellation of Coma Berenices. It was discovered by the German astronomer Heinrich Louis d'Arrest on April 22, 1865. John L. E. Dreyer described it as "faint, small, a little extended, 9th magnitude star to southwest". This object is located at a distance of approximately 309 megalight-years from the Milky Way. It is a member of the Coma cluster of galaxies, positioned around 18′ to the north of the cluster's center with no nearby galactic neighbors.
NGC 1316 is a lenticular galaxy about 60 million light-years away in the constellation Fornax. It is a radio galaxy and at 1400 MHz is the fourth-brightest radio source in the sky.
Arp 107 is a pair of interacting galaxies located about 450 million light-years away in the constellation Leo Minor. The galaxies are in the process of colliding and merging.
NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast". This is a relatively nearby galaxy, lying approximately 72 million light-years away from the Milky Way. It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago. NGC 4639 is a member of the Virgo Cluster.
NGC 4605 is a dwarf barred spiral galaxy in the constellation Ursa Major, located at a distance of 18.1 ± 0.3 megalight-years from the Milky Way. Physically it is similar in size and in B-band absolute magnitude to the Large Magellanic Cloud. It is a member of the M81 Galaxy Group, along with Messier 81 and Messier 101.
The Dorado Group is a loose concentration of galaxies containing both spirals and ellipticals. It is generally considered a 'galaxy group' but may approach the size of a 'galaxy cluster'. It lies primarily in the southern constellation Dorado and is one of the richest galaxy groups of the Southern Hemisphere. Gérard de Vaucouleurs was the first to identify it in 1975 as a large complex nebulae II in the Dorado region, designating it as G16.
NGC 5584 is a barred spiral galaxy in the constellation Virgo. It was discovered July 27, 1881 by American astronomer E. E. Barnard. Distance determination using Cepheid variable measurements gives an estimate of 75 million light years, whereas the tip of the red-giant branch approach yields a distance of 73.4 million light years. It is receding with a heliocentric radial velocity of 1,637 km/s. It is a member of the Virgo III Groups, a series of galaxies and galaxy clusters strung out to the east of the Virgo Supercluster of galaxies.
NGC 1404 is an elliptical galaxy in the Southern constellation Eridanus. It was discovered on November 28, 1837, by the astronomer John Herschel. Based on the tip of the red-giant branch distance indicator, it lies at a distance of approximately 60 million light-years from the Milky Way. It is one of the brightest members of the Fornax Cluster.
NGC 922 is a peculiar galaxy in the southern constellation of Fornax, located at a distance of 142 Mly from the Milky Way. It is one of the nearest known collisional galaxies. This object was described by the Herschels as "considerably faint, pretty large, round, gradually pretty much brighter middle." The general form is described by the morphological classification of SB(s)cd pec, which indicates a peculiar (pec) barred spiral galaxy (SB) with no inner ring system around the bar (s) and loosely-wound spiral arms (cd).
UGC 2885 is a large barred spiral galaxy of type SA(rs)c in the constellation Perseus. It is 232 million light-years (71 Mpc) from Earth and measures 463,000 ly (142,000 pc) across, making it one of the largest known spiral galaxies. It is also a possible member of the Pisces-Perseus supercluster.
NGC 2748 is a spiral galaxy in the northern circumpolar constellation of Camelopardalis, located at a distance of 61.3 megalight-years from the Milky Way. It was discovered September 2, 1828 by John Herschel. The morphological classification of SAbc indicates this is an unbarred spiral with moderate to loosely-wound spiral arms. It is a disk-like peculiar galaxy with a stellar shell that is rotating about the main galactic axis. This shell was most likely formed through the capture and disruption of a dwarf companion. The galactic nucleus likely contains a supermassive black hole with a mass of 4.4+3.5
−3.6×107 M☉, or 44 million times the mass of the Sun.
NGC 289 is a spiral galaxy in the southern constellation of Sculptor, located at a distance of 76 megalight-years from the Milky Way. It was discovered on September 27, 1834, by John Herschel. The compiler of the New General Catalogue, John Louis Emil Dreyer, noted that NGC 289 was "pretty bright, large, extended, between 2 considerably bright stars". The plane of the galaxy is inclined by an angle of 45° to the line of sight from the Earth.
NGC 672 is a spiral galaxy in the northern constellation of Triangulum, positioned around 2° to the southwest of the star Alpha Trianguli. The original object designated NGC 672 was discovered by the German-born astronomer William Herschel on 26 October 1786, but this was later cataloged as NGC 614. The object now identified as NGC 672 was discovered by John Herschel on 11 November 1827.
NGC 986 is a barred spiral galaxy in the southern constellation of Fornax, located about 76 million light-years away. It was discovered on August 5, 1826, by the Scottish astronomer James Dunlop, who described it as a "faint nebula, of an irregular round figure". The galaxy has an angular size of 3′.8 × 1′.9 with a visual magnitude of 10.9. It belongs to the Fornax Cluster of galaxies. This galaxy has a nearby companion, NGC 986A, at an angular separation of 17′, corresponding to a projected separation of 110 kpc. The two appear unconnected.
NGC 6753 is a massive unbarred spiral galaxy, seen almost exactly face-on, in the southern constellation of Pavo. It was discovered by the English astronomer John Herschel on July 5, 1836. The galaxy is located at a distance of 142 million light years from the Milky Way, and is receding with a heliocentric radial velocity of 3,140 km/s. It does not display any indications of a recent interaction with another galaxy or cluster.
NGC 2865 is an isolated elliptical galaxy in the equatorial constellation of Hydra. The core region of the galaxy shows a kinematically distinct component showing indications of a recent accretion or merger event that led to a burst of star formation around the nucleus. Observational constraints require this to have occurred within the last 100–400 million years, with the merger most likely being an Sb or Sc-class spiral galaxy.
NGC 1326 is a lenticular galaxy in the constellation Fornax, 63 million light-years away. It was discovered by English astronomer John Herschel on 29 November 1837. It is a member of the Fornax Cluster, an NGC 1316 subgroup and has a diameter of 70 000 light-years.
NGC 3818 is an elliptical galaxy in the Constellation Virgo. It is at a distance of about 118 million light-years away from Earth. In the center of NGC 3818 lies a supermassive black hole. NGC 3818 was discovered by William Herschel on March 5, 1785.
