NGC 3227 | |
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![]() Hubble Space Telescope image of NGC 3227 (left) and NGC 3226 (right) | |
Observation data (J2000 epoch) | |
Constellation | Leo |
Right ascension | 10h 23m 30.6s [1] |
Declination | +19° 51′ 54″ [1] |
Redshift | 1157 ± 3 km/s [1] |
Distance | 77 ± 9 Mly (24 ± 3 Mpc) [2] |
Apparent magnitude (V) | 11.1 [1] |
Characteristics | |
Type | SAB(s) pec [1] |
Apparent size (V) | 5.4′ × 3.6′ [1] |
Other designations | |
UGC 5620, [1] PGC 30445, [1] Arp 94 [1] |
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 . [3] 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. [4]
Sir William Herschel already recognised them as a 'double nebula'[ citation needed ] and they were jointly listed as Holm 187 in the Catalogue of Double and Multiple Galaxies and as Arp 94 in the Atlas of Peculiar Galaxies. Amateur telescopes can discern them but require magnification of about 100 times. They are situated 50′ east of the well-known double star system Gamma Leonis (i.e. Algieba).
One supernova has been observed in NGC 3227: SN 1983U (type Ia, mag. 12). [5] [6]
NGC 3227 contains a Seyfert nucleus, a type of active galactic nucleus (AGN). [7] Such Seyfert nuclei typically contain supermassive black holes. This object has an estimated mass of 1.4+1.0
−0.6×107 M☉ . [8]
As is typical of many AGN, the nucleus of NGC 3227 has been identified as a source of variable X-ray emission. [9] [10] [11] [12] [13] This variability occurs on time scales ranging from a few hours to a few months. [9] [11] [12] [13] The variability may be caused by variations in the density or ionization of gas and dust near the AGN that absorb the X-ray emission. [10] [11] [12] [13] A substantial amount of the X-ray-absorbing gas may lie within 0.4 parsec (1.3 light-years) of the nucleus. [13] An observed change in the shape of the X-ray spectrum in 2000 and 2001 suggests that some of the X-ray absorbing gas is located within 10–100 light-days of the nucleus. [14]
The luminosity of the nucleus reached a maximum in 1977 when evidence suggesting long-lived one-sided or two-sided gas streams was obtained. X-ray radiation of the central accretion disc is reprocessed in one to two days to be re-emitted in the optical spectrum. Infra-red light emission from the hot dust torus lags optical light emission from the nucleus by about 20 days in NGC 3227. The temperature of the dust torus is estimated at 1500 K to 1800 K in NGC 3227 and similar galaxies.
This galaxy was studied by the Multicolor Active Galactic Nuclei Monitoring 2m telescope. [15]
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such excess, non-stellar emissions have been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy.
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasar host galaxies. They have quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.
NGC 4395 is a nearby low surface brightness spiral galaxy located about 14 million light-years from Earth in the constellation Canes Venatici. The nucleus of NGC 4395 is active and the galaxy is classified as a Seyfert Type I known for its very low-mass supermassive black hole.
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 5548 is a Type I Seyfert galaxy with a bright, active nucleus. This activity is caused by matter flowing onto a 65 million solar mass (M☉) supermassive black hole at the core. Morphologically, this is an unbarred lenticular galaxy with tightly-wound spiral arms, while shell and tidal tail features suggest that it has undergone a cosmologically-recent merger or interaction event. NGC 5548 is approximately 245 million light years away and appears in the constellation Boötes. The apparent visual magnitude of NGC 5548 is approximately 13.3 in the V band.
NGC 3783 is a barred spiral galaxy located about 135 million light years away in the constellation Centaurus. It is inclined by an angle of 23° to the line of sight from the Earth along a position angle of about 163°. The morphological classification of SBa indicates a bar structure across the center (B) and tightly-wound spiral arms (a). Although not shown by this classification, observers note the galaxy has a luminous inner ring surrounding the bar structure. The bright compact nucleus is active and categorized as a Seyfert 1 type. This nucleus is a strong source of X-ray emission and undergoes variations in emission across the electromagnetic spectrum.
NGC 4698 is a barred spiral galaxy located around 55 million light years away from Earth in the constellation of Virgo. It belongs to the Virgo Cluster of galaxies and is positioned near the northeastern edge of this assemblage. The morphological classification of NGC 4698 in the De Vaucouleurs system is SA(s)ab, which indicates a purely spiral structure with moderate to tightly wound arms. It is inclined to the line of sight from the Earth by an angle of 53° along a position angle of 170°.
NGC 708 is an elliptical galaxy located 240 million light-years away in the constellation Andromeda and was discovered by astronomer William Herschel on September 21, 1786. It is classified as a cD galaxy and is the brightest member of Abell 262. NGC 708 is a weak FR I radio galaxy and is also classified as a type 2 Seyfert galaxy.
NGC 7469 is an intermediate spiral galaxy in the constellation of Pegasus. NGC 7469 is located about 200 million light-years away from Earth, which means, given its apparent dimensions, that NGC 7469 is approximately 90,000 light-years across. It was discovered by William Herschel on November 12, 1784.
NGC 3367 is a barred spiral galaxy located in the constellation Leo. It is located at a distance of about 120 million light years from Earth, which, given its apparent dimensions, means that NGC 3367 is about 85,000 light years across. It was discovered by William Herschel on March 19, 1784.
NGC 7213 is a lenticular galaxy located in the constellation Grus. It is located at a distance of circa 70 million light-years from Earth, which, given its apparent dimensions, means that NGC 7213 is about 75,000 light-years across. It was discovered by John Herschel on September 30, 1834. It is an active galaxy with characteristics between a type I Seyfert galaxy and LINER.
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.
NGC 1386 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 53 million light years from Earth, which, given its apparent dimensions, means that NGC 1386 is about 50,000 light years across. It is a Seyfert galaxy, the only one in Fornax Cluster.
NGC 4278 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4278 is about 65,000 light years across. It was discovered by William Herschel on March 13, 1785. NGC 4278 is part of the Herschel 400 Catalogue and can be found about one and 3/4 of a degree northwest of Gamma Comae Berenices even with a small telescope.
NGC 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of circa 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across. It was discovered by Nils Dunér on September 15, 1867.
NGC 2617 is a Seyfert galaxy in the equatorial constellation of Hydra. It was discovered on February 12, 1885, by French astronomer Édouard Stephan. In 1888, Danish astronomer J. L. E. Dreyer described it as "extremely faint, very small, 2 very faint stars involved". It is located at an estimated distance of 202 million light years. In the infrared, the galaxy has an angular size of 0.693 by 0.652 arcminutes.
NGC 7172 is a spiral galaxy located in the constellation Piscis Austrinus. It is located at a distance of about 110 million light years from Earth, which, given its apparent dimensions, means that NGC 7172 is about 100,000 light years across. It was discovered by John Herschel on September 23, 1834.
NGC 3516 is a barred lenticular galaxy in the constellation of Ursa Major. NGC 3516 is located about 150 million light years away from Earth, which means, given its apparent dimensions, that NGC 3516 is approximately 100,000 light years across. It was discovered by William Herschel on April 3, 1785.
Markarian 590, also known as NGC 863, NGC 866, and NGC 885, is a spiral galaxy located in the constellation Cetus. It is located at a distance of about 300 million light years from Earth, which, given its apparent dimensions, means that NGC 863 is about 110,000 light years across. It is a change looking Seyfert galaxy.
NGC 4253 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 185 million light years from Earth, which, given its apparent dimensions, means that NGC 4253 is about 65,000 light years across. It was discovered by William Herschel on February 3, 1788. It is a Seyfert galaxy.