IC 2006 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Eridanus |
Right ascension | 03h 54m 28.427s [1] |
Declination | −35° 58′ 01.75″ [1] |
Redshift | 0.004610 [2] |
Helio radial velocity | 1382 [2] |
Distance | 65.36 ± 0.46 Mly (20.04 ± 0.14 Mpc) [3] |
Group or cluster | Fornax Cluster [3] |
Apparent magnitude (B) | 12.39 [4] |
Characteristics | |
Type | E1 [5] |
Size | 35 000 light-years in diameter |
Apparent size (V) | 2.1′ × 1.8′ [2] |
Notable features | Early-type galaxy |
Other designations | |
AM 0532-360, MGC-06-09-037, PGC 14077 |
IC 2006 is an elliptical galaxy in the constellation Eridanus. The galaxy was discovered on 3 October 1897 by the American astronomer Lewis A. Swift. [6] It is estimated to be around 60 to 70 million light years (20 megaparsecs) away, [2] in the Fornax Cluster. [3] The galaxy is one of the smaller in the Fornax cluster, with a diameter of only 35 000 light-years.
IC 2006 is an early-type galaxy with a Hubble classification of E1, [5] but has also been listed as a lenticular galaxy with a morphological type of SA0−. [2] Despite their name, early-type galaxies are much older than spiral galaxies, and mostly comprise old, red-colored stars. Very little star formation occurs in these galaxies; the lack of star formation in elliptical galaxies appears to start at the center and then slowly propagates outward. [7] Its age is estimated to be 8.1 ± 1.7 billion years. [8]
An image taken by the Hubble Space Telescope in 2015 shows a characteristically smooth profile, with no spiral arms. [9] However, IC 2006 has a ring surrounding it. The ring appears to rotate in a direction opposite to the rest of the body, but this may be explained by a polar ring with an elliptical shape. [10]
The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1022 metres), 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 kpc (3×10 6 ly; 2×1022 m) 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.
Messier 105 or M105, also known as NGC 3379, is an elliptical galaxy 36.6 million light-years away in the equatorial constellation of Leo. It is the biggest elliptical galaxy in the Messier catalogue that is not in the Virgo cluster. It was discovered by Pierre Méchain in 1781, just a few days after he discovered the nearby galaxies Messier 95 and Messier 96. This galaxy is one of a few not object-verified by Messier so omitted in the editions of his Catalogue of his era. It was appended when Helen S. Hogg found a letter by Méchain locating and describing this object which matched those aspects under its first-published name, NGC 3379.
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.
NGC 2787 is a barred lenticular galaxy approximately 24 million light-years away in the northern constellation of Ursa Major. It was discovered on December 3, 1788 by German-born astronomer William Herschel. J. L. E. Dreyer described it as, "bright, pretty large, a little extended 90°, much brighter middle, mottled but not resolved, very small (faint) star involved to the southeast". The visible galaxy has an angular size of 2′.5 × 1′.5 and an apparent visual magnitude of 11.8.
NGC 3607 is a small but fairly bright lenticular galaxy in the equatorial constellation of Leo, about 2.5° south of the prominent star Delta Leonis. The galaxy was discovered March 14, 1784 by William Herschel. Dreyer described it as "very bright, large, round, very much brighter middle, 2nd of 3". It is located at a distance of 73 million light years and is receding with a radial velocity of 930 km/s. The galaxy lies southwest of NGC 3626 at an angular separation of ~50′. It occupies the center of the Leo II Group of galaxies, forming one of its two brightest members – the other being NGC 3608. It is a member of the NGC 3607 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.
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 6263 is an elliptical galaxy in the constellation Hercules. It was discovered by Albert Marth on June 28, 1864.
The Eridanus Cluster is a galaxy cluster roughly 23 Mpc (75 Mly) from Earth, containing about 73 main galaxies and about 200 total galaxies. About 30% have Hubble classifications of elliptical or S0 and the remaining 70% are spiral or irregular. These galaxies reside in smaller groups which are all loosely gravitationally bound to each other, suggesting that the system is still condensing from the Hubble flow and may eventually form a cluster of about 1014M☉. A low velocity dispersion compared to that of, for example, the Coma cluster, supports this hypothesis. The Eridanus Cluster is located in the constellation Eridanus near the Fornax Cluster, and is sometimes called the "Fornax II Cluster".
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.
IC 755, also known as NGC 4019, is a barred spiral galaxy. It lies about 60 million light-years away in the northern constellation of Coma Berenices. It is a member of the Virgo 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).
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 4203 is the New General Catalogue identifier for a lenticular galaxy in the northern constellation of Coma Berenices. It was discovered on March 20, 1787 by English astronomer William Herschel, and is situated 5.5° to the northwest of the 4th magnitude star Gamma Comae Berenices and can be viewed with a small telescope. The morphological classification of NGC 4203 is SAB0−, indicating that it has a lenticular form with tightly wound spiral arms and a weak bar structure at the nucleus.
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 770 is an elliptical galaxy in the constellation Aries. It is around 120 million light years from the Milky Way and has a diameter of around 36,000 ly. NGC 770 is gravitationally linked to NGC 772. The galaxy was discovered on November 3, 1855 by RJ Mitchell.
NGC 2950 is a lenticular galaxy in the northern constellation of Ursa Major, about 50 million light years from the Milky Way and receding with a heliocentric radial velocity of 1,329 km/s. It was discovered in 1790 by the Anglo-German astronomer William Herschel. NGC 2950 is a field galaxy, it is not part of a galaxy cluster or galaxy group, and thus is gravitationally isolated. Nine certain and four possible dwarf galaxies have been identified around NGC 2950.
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.