NGC 4567 and NGC 4568 | |
---|---|
Observation data (J2000.0 epoch) | |
Constellation | Virgo |
Right ascension | 12h 36m 34.3s |
Declination | +11° 14′ 17″ |
Distance | 62 Mly (19.1 Mpc) [1] |
Apparent magnitude (V) | +10.9 |
Absolute magnitude (V) | -13.3 |
Characteristics | |
Type | SA(rs)bc / SA(rs)bc |
Apparent size (V) | 4.6′ × 2.1′ |
Notable features | colliding galaxies |
Other designations | |
NGC 4567/8, UGC 7776/7, PGC 42064/9, VV 219, [2] KPG 347, [3] Butterfly Galaxies, [4] Siamese Twin Galaxies, Siamese Twins Galaxies, Siamese Twins [5] [NB 1] |
NGC 4567 and NGC 4568 (nicknamed the Butterfly Galaxies [4] or Siamese Twins [NB 1] [5] ) are a set of unbarred spiral galaxies about 60 million light-years away [1] in the constellation Virgo. They were both discovered by William Herschel in 1784. They are part of the Virgo Cluster of galaxies.
These galaxies are in the process of colliding and merging with each other, as studies of their distributions of neutral and molecular hydrogen show, with the highest star-formation activity in the part where they overlap. However, the system is still in an early phase of interaction. [6] In about 500 million years the galaxies will coalesce into a single elliptical galaxy. [7]
Four supernovae have been observed in the Butterfly Galaxies:
The two galaxies were nicknamed "Siamese Twins" because they appear to be connected. On August 5, 2020, NASA announced that they would not use that nickname in an effort to avoid systemic discrimination in their terminology. [14] [15]
Messier 99 or M99, also known as NGC 4254 or St. Catherine's Wheel, is a grand design spiral galaxy in the northern constellation Coma Berenices approximately 15,000,000 parsecs from the Milky Way. It was discovered by Pierre Méchain on 17 March 1781. The discovery was then reported to Charles Messier, who included the object in the Messier Catalogue of comet-like objects. It was one of the first galaxies in which a spiral pattern was seen. This pattern was first identified by Lord Rosse in the spring of 1846.
NGC 3184, the Little Pinwheel Galaxy, is a spiral galaxy approximately 40 million light-years away in the constellation Ursa Major. Its name comes from its resemblance to the Pinwheel Galaxy. It was discovered on 18 March 1787 by German-British astronomer William Herschel. It has two HII regions named NGC 3180 and NGC 3181.
The Antennae Galaxies are a pair of interacting galaxies in the constellation Corvus. They are currently going through a starburst phase, in which the collision of clouds of gas and dust, with entangled magnetic fields, causes rapid star formation. They were discovered by William Herschel in 1785.
NGC 7479 is a barred spiral galaxy about 105 million light-years away in the constellation Pegasus. William Herschel discovered it in 1784. NGC 7479 is also recognized as a Seyfert galaxy and a LINER undergoing starburst activity not only on the nucleus and the outer arms, but also across the bar of the galaxy, where most of the stars were formed in the last 100 million years. Polarization studies of this galaxy indicate that it recently underwent a minor merger and that it is unique in the radio continuum, with arms opening in a direction opposite to the optical arms. This feature, along with the asymmetrical arms of the galaxy and the intense star formation activity are attributed to a merger with a smaller galaxy. This galaxy is similar in both size and morphology to the barred spiral NGC 1300.
NGC 6744 is an intermediate spiral galaxy in the constellation Pavo (Peacock). Its velocity with respect to the cosmic microwave background is 802 ± 3 km/s, which corresponds to a Hubble distance of 38.6 ± 2.7 Mly (11.82 ± 0.83 Mpc). However, 21 non redshift measurements give a distance of 23.63 ± 1.68 Mly (7.244 ± 0.514 Mpc). It was discovered on 30 June 1826 by Scottish astronomer James Dunlop, observing from Parramatta, Australia.
NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on 12 April 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.
Arp 87 is a pair of interacting galaxies, NGC 3808A and NGC 3808B. They are situated in the Leo constellation. NGC 3808A, the brighter, is a peculiar spiral galaxy, while NGC 3808B is an irregular galaxy.
NGC 935 and IC 1801 are a pair of interacting galaxies within the Aries constellation. They were discovered on 18 September 1885 by Lewis Swift. NGC 935 is the northern member of the pair, and IC 1801 is the southern. Together, they are listed in Halton Arp's Atlas of Peculiar Galaxies as Arp 276, as an example of interacting galaxies.
Arp 271 is a pair of similarly sized interacting spiral galaxies, NGC 5426 and NGC 5427, in the constellation of Virgo. It is not certain whether the galaxies are going to eventually collide or not. They will continue interacting for tens of millions of years, creating new stars as a result of the mutual gravitational attraction between the galaxies, a pull seen in the bridge of stars already connecting the two. Located about 130 million light-years away, the Arp 271 pair is about 130,000 light-years across. It was originally discovered in 1785 by William Herschel. It is speculated, that the Milky Way will undergo a similar collision in about five billion years with the neighbouring Andromeda Galaxy, which is currently located about 2.6 million light-years away.
NGC 7714 is a spiral galaxy in the constellation Pisces. Its velocity with respect to the cosmic microwave background is 2430 ± 26 km/s, which corresponds to a Hubble distance of 116.9 ± 8.3 Mly (35.85 ± 2.54 Mpc). In addition, five non-redshift measurements give a distance of 92.24 ± 8.69 Mly (28.280 ± 2.664 Mpc). It was discovered by British astronomer John Herschel on 18 September 1830.
NGC 6221 is a barred spiral galaxy located in the constellation Ara. In de Vaucouleurs' galaxy morphological classification scheme, it is classified as SB(s)bc and was discovered by British astronomer John Herschel on 3 May 1835. NGC 6221 is located at about 69 million light years from Earth.
NGC 150 is a barred spiral galaxy in the constellation Sculptor. It is about 70 million light years away from the Solar System, and it has a diameter of about 55,000 light years. It was discovered on 20 November 1886, by Lewis A. Swift.
NGC 7083 is an unbarred spiral galaxy located about 134 million light-years away in the constellation of Indus. It is also classified as a flocculent spiral galaxy. NGC 7083 was discovered by astronomer James Dunlop on August 28, 1826.
NGC 4647 is an intermediate spiral galaxy estimated to be around 63 million light-years away in the constellation of Virgo. It was discovered by astronomer William Herschel on March 15, 1784. NGC 4647 is listed along with Messier 60 as being part of a pair of galaxies called Arp 116; their designation in Halton Arp's Atlas of Peculiar Galaxies. The galaxy is located on the outskirts of the Virgo Cluster.
NGC 819 is a spiral galaxy approximately 302 million light-years away from Earth in the constellation of Triangulum. It forms a visual pair with the galaxy NGC 816 5.7' WNW.
NGC 5331 is a pair of two interacting spiral galaxies in the constellation Virgo. They were discovered by William Herschel on May 13, 1793.
NGC 4900 is a barred spiral galaxy in the constellation Virgo. It was discovered by William Herschel on April 30, 1786. It is a member of the NGC 4753 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster.
NGC 991 is an intermediate spiral galaxy the constellation Cetus. This galaxy was discovered by astronomer William Herschel in 1785.
NGC 767 is a barred spiral galaxy located in the constellation Cetus about 241 million light years from the Milky Way. It was discovered by the American astronomer Francis Leavenworth in 1886.
NGC 6365 is a pair of spiral galaxies in the constellation Draco. It consists of two galaxies, PGC 60174 to the south, and PGC 60171 to the north. These two galaxies are also designated respectively by the NASA/IPAC database as NGC 6365A and NGC 6365B. This pair of galaxies was discovered by German astronomer Lewis Swift in 1884.