NGC 520 | |
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![]() NGC 520 by HST | |
Observation data (J2000 epoch) | |
Constellation | Pisces |
Right ascension | 01h 24m 35.071s [1] |
Declination | +03° 47′ 32.68″ [1] |
Redshift | 0.007609±0.000010 [2] |
Heliocentric radial velocity | 2,281±3 km/s [2] |
Distance | 105 Mly (32.2 Mpc) [3] |
Apparent magnitude (V) | 12.2 [4] |
Characteristics | |
Type | Pec [4] |
Apparent size (V) | 4.5′ [4] |
Notable features | Interacting galaxies |
Other designations | |
UGC 966, Arp 157, [5] PGC 5193 [4] |
NGC 520, also known as the Flying Ghost, [6] is a pair of colliding spiral galaxies about 105 million light-years away in the constellation Pisces. [7] They were discovered by astronomer William Herschel on 13 December 1784. [8]
Halton Arp called this the second-brightest very disturbed galaxy in the sky, and it is as bright in the infrared and radio bands as the Antennae Galaxies. Simulations indicate this object consists of two galactic disks that began interacting about 300 million years ago. The system is still in an early stage of its merger, showing two separate velocity systems in the spectra, and two small tails. Two galactic nuclei have been detected, [9] and one is an H II nucleus. [10]
The main galactic component is being viewed edge-on, making it fainter in the optical band. The secondary component is brighter but less massive than the main, and is located to the northwest. They are separated by a dark lane of dust. The region of the galaxies outside their nuclei experienced a period of increased star formation roughly around the time they began to interact. [9] Two dwarf objects are located in the vicinity of this merging pair, and one of them, designated UGC957, is located in the northern tidal tail – it may be the result of the interaction. [11]
When viewed in the X-ray band, the interacting galaxies appear around half as luminous as expected given their merger state. Analysis of the gas and molecular features suggests the secondary merger component is gas poor. Most of the star formation, therefore, took place in the gas-rich main component to the southeast. 15 X-ray sources are detected within the merger, with many of them displaying long-term variability. A large galactic wind is evident, being driven by the starburst activity. [9]
Messier 59 or M59, also known as NGC 4621, is an elliptical galaxy in the equatorial constellation of Virgo. It is a member of the Virgo Cluster, with the nearest fellow member 8′ away and around 5 magnitudes fainter. The nearest cluster member of comparable brightness is the lenticular galaxy NGC 4638, which is around 17′ away. It and the angularly nearby elliptical galaxy Messier 60 were both discovered by Johann Gottfried Koehler in April 1779 when observing comet seeming close by. Charles Messier listed both in the Messier Catalogue about three days after Koehler's discovery.
NGC 185 is a dwarf spheroidal galaxy located 2.08 million light-years from Earth, appearing in the constellation Cassiopeia. It is a member of the Local Group, and is a satellite of the Andromeda Galaxy (M31). NGC 185 was discovered by William Herschel on November 30, 1787, and he cataloged it "H II.707". John Herschel observed the object again in 1833 when he cataloged it as "h 35", and then in 1864 when he cataloged it as "GC 90" within his General Catalogue of Nebulae and Clusters. NGC 185 was first photographed between 1898 and 1900 by James Edward Keeler with the Crossley Reflector of Lick Observatory. Unlike most dwarf elliptical galaxies, NGC 185 contains young stellar clusters, and star formation proceeded at a low rate until the recent past. NGC 185 has an active galactic nucleus (AGN) and is usually classified as a type 2 Seyfert galaxy, though its status as a Seyfert is questioned. It is possibly the closest Seyfert galaxy to Earth, and is the only known Seyfert in the Local Group.
NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
NGC 3226 is a dwarf elliptical galaxy that is interacting with the spiral galaxy NGC 3227. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
NGC 3486 is an intermediate barred spiral galaxy located about 27.4 million light years away in the constellation of Leo Minor. It has a morphological classification of SAB(r)c, which indicates it is a weakly barred spiral with an inner ring and loosely wound arms. This is a borderline, low-luminosity Seyfert galaxy with an active nucleus. However, no radio or X-ray emission has been detected from the core, and it may only have a small supermassive black hole with less than a million times the mass of the Sun.
NGC 4194, the Medusa merger, is a galaxy merger in the constellation Ursa Major about 128 million light-years (39.1 Mpc) away. It was discovered on April 2, 1791 by German-British astronomer William Herschel. Due to its disturbed appearance, it is object 160 in Halton Arp's 1966 Atlas of Peculiar Galaxies.
NGC 3432 is an edge-on spiral galaxy that can be found in the northern constellation of Leo Minor. It was discovered by German-British astronomer William Herschel on March 19, 1787. This galaxy is located at a distance of 40 million light-years (12.3 Mpc) from the Milky Way. It is interacting with UGC 5983, a nearby dwarf galaxy, and features tidal filaments and intense star formation. Because of these features, it was listed in Halton Arp's Atlas of Peculiar Galaxies.
NGC 3169 is a spiral galaxy about 75 million light years away in the constellation Sextans. It has the morphological classification SA(s)a pec, which indicates this is a pure, unbarred spiral galaxy with tightly-wound arms and peculiar features. There is an asymmetrical spiral arm and an extended halo around the galaxy. It is a member of the NGC 3166 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
NGC 5614 is an unbarred spiral galaxy in the constellation Boötes. It is the primary member of the Arp 178 triplet of interacting galaxies with NGC 5613 and NGC 5615.
NGC 5752 is a spiral galaxy in the constellation Boötes. It is a member of the Arp 297 interacting galaxies group which comprises four galaxies: NGC 5752, NGC 5753, NGC 5754, NGC 5755.
NGC 3561, also known as Arp 105, is a pair of interacting galaxies NGC 3561A and NGC 3561B within the galaxy cluster Abell 1185 in Ursa Major. Its common name is "the Guitar" and contains a small tidal dwarf galaxy known as Ambartsumian's Knot that is believed to be the remnant of the extensive tidal tail pulled out of one of the galaxies.
NGC 2782 is a peculiar spiral galaxy that formed after a galaxy merger in the constellation Lynx. The galaxy lies 75 million light years away from Earth, which means, given its apparent dimensions, that NGC 2782 is approximately 100,000 light years across. NGC 2782 has an active galactic nucleus and it is a starburst and a type 1 Seyfert galaxy. NGC 2782 is mentioned in the Atlas of Peculiar Galaxies in the category galaxies with adjacent loops.
NGC 3256 is a peculiar galaxy formed from the collision of two separate galaxies in the constellation of Vela. NGC 3256 is located about 100 million light-years away and belongs to the Hydra–Centaurus Supercluster complex. NGC 3256 provides a nearby template for studying the properties of young star clusters in tidal tails. The system hides a double nucleus and a tangle of dust lanes in the central region. The telltale signs of the collision are two extended luminous tails swirling out from the galaxy. The tails are studded with a particularly high density of star clusters. NGC 3256 is the most luminous galaxy in the infrared spectrum located within z 0.01 from Earth.
NGC 720 is an elliptical galaxy located in the constellation Cetus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 720 is about 110,000 light years across. It was discovered by William Herschel on October 3, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies about three and a half degrees south and slightly east from zeta Ceti.
NGC 6621 is an interacting spiral galaxy in the constellation Draco. It lies at a distance of circa 260 million light-years. NGC 6621 interacts with NGC 6622, with their closest approach having taken place about 100 million years before the moment seen now. The pair was discovered by Edward D. Swift and Lewis A. Swift on June 2, 1885. Originally NGC 6621 was assigned to the southeast galaxy, but now it refers to the northern one. NGC 6621 and NGC 6622 are included in the Atlas of Peculiar Galaxies as Arp 81 in the category "spiral galaxies with large high surface brightness companions".
NGC 5363 is a lenticular galaxy located in the constellation Virgo. It is located at a distance of circa 65 million light years from Earth, which, given its apparent dimensions, means that NGC 5363 is about 100,000 light years across. It was discovered by William Herschel on January 19, 1784. It is a member of the NGC 5364 Group of galaxies, itself one of the Virgo III Groups strung out to the east of the Virgo Supercluster of galaxies.
NGC 1142 is a distorted spiral galaxy in the constellation of Cetus. It is located about 370 million light years away from Earth, which means, given its apparent dimensions, that NGC 1142 is approximately 170,000 light years across. It is a type 2 Seyfert galaxy. It interacts with the elliptical galaxy NGC 1141.
NGC 3656 is a peculiar galaxy formed by the collision of two galaxies in the constellation of Ursa Major. It is located about 135 million light years away from Earth, which means, given its apparent dimensions, that NGC 3656 is approximately 70,000 light years across. It was discovered by William Herschel on April 14, 1789.
NGC 7592 is an interacting galaxy system located 300 million light years away in the constellation Aquarius. It was discovered by William Herschel on September 20, 1784. The total infrared luminosity is 1011.33 L☉, and thus it is categorised as a luminous infrared galaxy. One of the galaxies hosts a type 2 Seyfert nucleus.
NGC 7513 is a barred spiral galaxy located in the constellation Sculptor. It is located at a distance of circa 62.5 million light years from Earth, which, given its apparent dimensions, means that NGC 7513 is about 75,000 light years across. It was discovered by Albert Marth on September 24, 1864.