NGC 2451 | |
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![]() NGC 2451 (taken from Stellarium) | |
Observation data (J2000 epoch) | |
Right ascension | 07h 45m 24.0s [1] |
Declination | −37° 57′ 00″ [1] |
Distance | 600 ly (NGC 2451A), 1,200 ly (NGC 2451B) [1] |
Apparent magnitude (V) | 3 [1] |
Apparent dimensions (V) | 45″ [1] |
Physical characteristics | |
Other designations | Cr 161 |
Associations | |
Constellation | Puppis |
NGC 2451 is an open cluster in the Puppis constellation, probably discovered by Giovanni Battista Hodierna before 1654 and John Herschel in 1835. [1] In 1994, it was postulated that this was actually two open clusters that lie along the same line of sight. This was confirmed in 1996. The respective clusters are labeled NGC 2451 A and NGC 2451 B, and they are located at distances of 600 and 1,200 light-years, respectively. [2]
Puppis ("stern") is a constellation in the southern sky. It was originally part of the traditional constellation of Argo Navis, which was divided into three parts, the other two being Carina, and Vela. Puppis is the largest of the three constellations in square degrees. It is one of the 88 modern constellations recognized by the International Astronomical Union.
The New General Catalogue of Nebulae and Clusters of Stars is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and emission nebulae. Dreyer published two supplements to the NGC in 1895 and 1908, known as the Index Catalogues, describing a further 5,386 astronomical objects. Thousands of these objects are best known by their NGC or IC numbers, which remain in widespread use.
Messier 35 or M35, also known as NGC 2168 or the Shoe-Buckle Cluster, is a relatively close open cluster of stars in the west of Gemini, at about the declination of the Sun when the latter is at June solstice. It was discovered by Philippe Loys de Chéseaux around 1745 and independently discovered by John Bevis before 1750. It is scattered over part of the sky almost the size of the full moon and is 2,970 light-years away. The compact open cluster NGC 2158 lies directly southwest of it.
NGC 752 is an open cluster in the constellation Andromeda. The cluster was discovered by Caroline Herschel in 1783 and cataloged by her brother William Herschel in 1786, although an object that may have been NGC 752 was described by Giovanni Batista Hodierna before 1654.
NGC 188 is an open cluster in the constellation Cepheus. It was discovered by John Herschel in 1825. Unlike most open clusters that drift apart after a few million years because of the gravitational interaction of our Milky Way galaxy, NGC 188 lies far above the plane of the galaxy and is one of the most ancient of open clusters known, at approximately 6.8 billion years old.
NGC 381 is an open cluster of stars in the northern constellation of Cassiopeia, located at a distance of approximately 3,120 light-years from the Sun. Credit for the discovery of this cluster was given to Caroline Herschel by her brother William in 1787, although she may never have actually seen it.
NGC 2362, also known as Caldwell 64, is an open cluster of stars in the southern constellation of Canis Major. It was discovered by the Italian court astronomer Giovanni Batista Hodierna, who published his finding in 1654. William Herschel called it a "beautiful cluster", while William Henry Smyth said it "has a beautiful appearance, the bright white star being surrounded by a rich gathering of minute companions, in a slightly elongated form, and nearly vertical position". In the past it has also been listed as a nebula, but in 1930 Robert J. Trumpler found no evidence of nebulosity. The brightest member star system is Tau Canis Majoris, and therefore it is sometimes called the Tau Canis Majoris Cluster.
NGC 2477 is an open cluster in the constellation Puppis. It contains about 300 stars, and was discovered by Abbé Lacaille in 1751. The cluster's age has been estimated at 700 million years.
NGC 869 is an open cluster located 7460 light years away in the constellation of Perseus. The cluster is about 14 million years old. It is the westernmost of the Double Cluster with NGC 884.
NGC 884 is an open cluster located 7640 light years away in the constellation of Perseus. It is the easternmost of the Double Cluster with NGC 869. NGC 869 and 884 are often designated h and χ Persei, respectively. The cluster is about 14 million years old. Located in the Perseus OB1 association, both clusters are located physically close to one another, only a few hundred light years apart. The clusters were first recorded by Hipparchus, thus have been known since antiquity.
NGC 6633 is a large bright open cluster in the constellation Ophiuchus. Discovered in 1745-46 by Philippe Loys de Chéseaux, it was independently rediscovered by Caroline Herschel in 1783 and included in her brother William's catalog as H VIII.72. Bright enough to be seen with the naked eye, the cluster is considered a fine object for binoculars or small telescopes.
The Double Cluster consists of the open clusters NGC 869 and NGC 884, which are close together in the constellation Perseus. Both visible with the naked eye, NGC 869 and NGC 884 lie at a distance of about 7,500 light years in the Perseus Arm of the Milky Way galaxy.
NGC 2244 is an open cluster in the Rosette Nebula, which is located in the constellation Monoceros. This cluster has several O-type stars, super hot stars that generate large amounts of radiation and stellar wind.
NGC 3293 is an open cluster in the Carina constellation. It was discovered by Nicolas-Louis de Lacaille in 1751. It consists of more than 100 stars brighter than 14th magnitude in a 10 arc minute field, the brightest of which are blue supergiants of apparent magnitude 6.5 and 6.7. There is also a 7th magnitude pulsating red supergiant, V361 Carinae.
NGC 6025 is an open cluster of stars in the southern constellation of Triangulum Australe, near the northern constellation border with Norma. It was discovered by Abbe Lacaille in 1751 during his expedition to the Cape of Good Hope. The cluster is in the Caldwell catalogue as entry number 95, and is located at a mean distance of 2,410 ly from the Sun. NGC 6025 can be spotted with the naked eye, but is better viewed with a set of large binoculars. It has an apparent visual magnitude of 5.1 and spans an angular size of 15′.
De systemate orbis cometici, deque admirandis coeli characteribus is a small tract on comets and other celestial objects by the Sicilian astronomer Giovanni Battista Hodierna published in 1654. It contains a catalogue of comets and other celestial objects, but had limited circulation and the work was forgotten until 1985. In this work, Hodierna expressed the belief that comets were made of a more terrestrial substance, and considered nebulae to be made up of stars.
NGC 1528 is an open cluster in the constellation Perseus. It was discovered by William Herschel in 1790. It is located in the north-eastern part of the constellation, just under 3 degrees north of μ Persei. Less than 1.5° to the southeast is the open cluster NGC 1545. The NGC 1528 is clearly visible with 10x50 binoculars. 165 stars are recognised as members of NGC 1528, the brightest of which has apparent magnitude 8.7.
NGC 654 is an open cluster in the constellation Cassiopeia. It was discovered by William Herschel in 1787. With apparent magnitude 6.5, it can be observed by binoculars. It is located 2,5° northeast of the star Delta Cassiopeiae. In the same low power field can also be seen the open clusters NGC 663 and NGC 659. It surrounds a 7th magnitude yellowish star, an F5Ia supergiant, which is a possible member of the group.
NGC 366 is an open cluster located in the constellation Cassiopeia. It was discovered on October 27, 1829, by John Herschel. It was described by Dreyer as a "cluster, small."