NGC 2293 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Canis Major |
Right ascension | 06h 47m 42.9s [1] |
Declination | −26° 45′ 16″ [1] |
Redshift | 0.006795 ± 0.000020 [1] |
Heliocentric radial velocity | 2037 ± 6 km/s [1] |
Distance | 107 ± 49 Mly (32.9 ± 15.0 Mpc) [1] |
Apparent magnitude (V) | 11.2 [2] |
Characteristics | |
Type | SAB(s)0+ pec [1] |
Apparent size (V) | 4.2′ × 3.3′ [1] |
Notable features | Interacts with NGC 2292 |
Other designations | |
ESO 490-IG 049, VV 178a, MCG -04-16-023, PGC 19619 [1] |
NGC 2293 is a lenticular galaxy located in the constellation Canis Major. It is located at a distance of circa 100 million light years from Earth, which, given its apparent dimensions, means that NGC 2293 is about 160,000 light years across. It was discovered by John Herschel on January 20, 1835. [3] NGC 2293 forms a pair with NGC 2292 and has an HI ring that surrounds both galaxies.
NGC 2293 is a lenticular galaxy with hints of a spiral structure. The old stars that make it give the galaxy an orange color. [4] Located 0.8 arcminutes away from NGC 2292 lies NGC 2293. Both galaxies appear to share a common envelope and a complete ring of neutral hydrogen gas (HI) has been found to encircle both galaxies. The ring apparently has a color change to the southwestern view, that has been attributed to the presence of star formation. On the other hand, there is a marked absence of HI near the centre of the two galaxies. [5] The total HI mass is 0.75×109 M☉. [5] [6]
It is possible that the ring is the result of an ongoing merger between the two galaxies, that would result in a giant elliptical galaxy. [5] Various models have been suggested for the formation of the ring. The most likely model is the collision between one of the two galaxies and one more galaxy that swept gas away, with the star formation region on the ring been created by a density wave or it is a population that was stripped by the intruder galaxy. [5] It has not been ruled out that the positioning is a projection effect of two galaxies separated by a few million light years. [5]
Based on far infrared observations there is an extensive amount of cold dust at the pair, with temperature 13 K, which is lower than dust temperatures found in spiral and interacting galaxies. The temperature indicates however that it is not of primordial origin. [6]
NGC 2292/2293 pair belongs to a galaxy group known as LGG 138. Other members of the group are the spiral galaxy NGC 2280, NGC 2295, ESO 490−G010 and ESO 490−G045. Because of its large angular diameter, about one degree, the group was identified when redshift information were available, by Garcia et al. in 1993. [7]
An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies. Elliptical (E) galaxies are, together with lenticular galaxies (S0) with their large-scale disks, and ES galaxies with their intermediate scale disks, a subset of the "early-type" galaxy population.
A lenticular galaxy is a type of galaxy intermediate between an elliptical and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. Lenticular galaxies are disc galaxies that have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks. As a result, they consist mainly of aging stars. Despite the morphological differences, lenticular and elliptical galaxies share common properties like spectral features and scaling relations. Both can be considered early-type galaxies that are passively evolving, at least in the local part of the Universe. Connecting the E galaxies with the S0 galaxies are the ES galaxies with intermediate-scale discs.
NGC 3115 is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it is several times bigger than the Milky Way. It is a lenticular (S0) galaxy because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar.
NGC 1097 is a barred spiral galaxy about 45 million light years away in the constellation Fornax. It was discovered by William Herschel on 9 October 1790. It is a severely interacting galaxy with obvious tidal debris and distortions caused by interaction with the companion galaxy NGC 1097A.
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 arcminutes or 3.24 × 1.81 arcminutes and an apparent visual magnitude of 11.8.
NGC 1808 is a barred spiral galaxy located in the southern constellation of Columba, about two degrees to the south and east of Gamma Caeli. It was discovered on 10 May 1826 by Scottish astronomer James Dunlop, who described it as a "faint nebula". The galaxy is a member of the NGC 1808 group, which is part of the larger Dorado Group.
NGC 3504 is a barred spiral galaxy in the constellation Leo Minor. It has a Hubble distance corresponding to 88 million light-years and was discovered by William Herschel in 1785.
NGC 1553 is a prototypical lenticular galaxy in the constellation Dorado. It is the second brightest member of the Dorado Group of galaxies. British astronomer John Herschel discovered NGC 1553 on December 5, 1834 using an 18.7 inch reflector.
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 7013 is a relatively nearby spiral or lenticular galaxy estimated to be around 37 to 41.4 million light-years away from Earth in the constellation of Cygnus. NGC 7013 was discovered by English astronomer William Herschel on July 17, 1784 and was also observed by his son, astronomer John Herschel on September 15, 1828.
NGC 2280 is a spiral galaxy located in the constellation Canis Major. It is located at a distance of about 75 million light years from Earth, which, given its apparent dimensions, means that NGC 2280 is about 135,000 light years across. It was discovered by John Herschel on February 1, 1835.
NGC 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of about 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.
NGC 6907 is a spiral galaxy located in the constellation Capricornus. It is located at a distance of about 120 million light-years from Earth, which, given its apparent dimensions, means that NGC 6907 is about 115,000 light-years across. It was discovered by William Herschel on July 12, 1784. The total infrared luminosity of the galaxy is 1011.03 L☉, and thus it is categorised as a luminous infrared galaxy.
NGC 3585 is an elliptical or a lenticular galaxy located in the constellation Hydra. It is located at a distance of circa 60 million light-years from Earth, which, given its apparent dimensions, means that NGC 3585 is about 80,000 light years across. It was discovered by William Herschel on December 9, 1784.
NGC 6902 is an unbarred spiral galaxy located in the southern constellation of Sagittarius at an approximate distance of 124 million light-years (38.0 Mpc). NGC 6902 was discovered on September 2, 1836 by English astronomer John Herschel. In his New General Catalogue, Danish astronomer J. L. E. Dreyer described it as faint, considerably small, round, brighter middle. It is a member of the small NGC 6092 group of galaxies; the LGG 434 group.
NGC 2974 is a lenticular galaxy located in the constellation Sextans. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 2974 is about 90,000 light years across. It was discovered by William Herschel on January 6, 1785. NGC 2974 is located in the sky about 2 and a half degrees south-south east of Iota Hydrae and more than 6 degrees northeast of Alphard. A 10th magnitude star lies next to the galaxy, thus making it a challenging object at low magnifications. NGC 2974 is part of the Herschel 400 Catalogue.
NGC 4299 is a featureless spiral galaxy located about 55 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.
NGC 4324 is a lenticular galaxy located about 85 million light-years away in the constellation Virgo. It was discovered by astronomer Heinrich d'Arrest on March 4, 1862. NGC 4324 has a stellar mass of 5.62 × 1010M☉, and a baryonic mass of 5.88 × 1010M☉. The galaxy's total mass is around 5.25 × 1011M☉. NGC 4324 is notable for having a ring of star formation surrounding its nucleus. It was considered a member of the Virgo II Groups until 1999, when its distance was recalculated and it was placed in the Virgo W Group.