NGC 869 | |
---|---|
Observation data (J2000 epoch) | |
Right ascension | 02h 19.1m [1] |
Declination | +57° 09′ [1] |
Distance | 7.5 kly [2] (2.3 kpc [2] ) |
Apparent magnitude (V) | 3.7 [1] |
Physical characteristics | |
Radius | 33.15 ly |
Estimated age | 14 Myr [2] |
Other designations | Caldwell 14, Cr 24, [1] Mel 13, [1] h Per, [1] h Persei [1] |
Associations | |
Constellation | Perseus |
NGC 869 (also known as h Persei) is an open cluster located 7460 light years away in the constellation of Perseus. [2] The cluster is about 14 million years old. [2] It is the westernmost of the Double Cluster with NGC 884.
NGC 869 and 884 are often designated h and χ (chi) Persei, respectively. Some confusion surrounds what Bayer intended by these designations. It is sometimes claimed that Bayer did not resolve the pair into two patches of nebulosity, and that χ refers to the Double Cluster and h to a nearby star. [3] Bayer's Uranometria chart for Perseus does not show them as nebulous objects, but his chart for Cassiopeia does, and they are described as Nebulosa Duplex in Schiller's Coelum Stellatum Christianum , which was assembled with Bayer's help. [4] The clusters are both located in the Perseus OB1 association, a few hundred light years apart from each other. The clusters were first recorded by Hipparchus, thus have been known since antiquity.
The Double Cluster is often photographed and observed with small telescopes. The clusters are visible with the unaided eye between the constellations of Perseus and Cassiopeia as a brighter patch in the winter Milky Way. In small telescopes the cluster appears as an assemblage of bright stars located in a rich star field. Dominated by bright blue stars, the cluster also hosts a few orange stars.
Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars.
Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux.
Cassiopeia is a constellation and asterism in the northern sky named after the vain queen Cassiopeia, mother of Andromeda, in Greek mythology, who boasted about her unrivaled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd-century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars.
Perseus is a constellation in the northern sky, named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was defined in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" shape similar to that of Cassiopeia, and it is thus sometimes referred to as 'Little Cassiopeia'. It is located between Cygnus, Cassiopeia and Andromeda on the northern celestial sphere. The northern part lies on the Milky Way.
Messier 103 is a small open cluster of many faint stars in Cassiopeia. It was discovered on 27 March 1781 by Pierre Méchain, but later added as Charles Messier's last deep-sky object in his catalogue.
NGC 7510 is an open cluster of stars located around 11,400 light years away in the constellation Cepheus, near the border with Cassiopeia. At this distance, the light from the cluster has undergone extinction from interstellar gas and dust equal to E(B – V) = 0.90 ± 0.02 magnitude in the UBV photometric system. Its brightest member is a giant star with a stellar classification of B1.5 III. This cluster forms part of the Perseus Spiral Arm. It has a Trumpler class rating of II 2 m and is around 10 million years old.
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.
This table lists those stars or other objects which have Bayer designations, grouped by the constellation part of the designation.
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.
Gemini is one of the constellations of the zodiac and is located in the northern celestial hemisphere. It was one of the 48 constellations described by the 2nd century AD astronomer Ptolemy, and it remains one of the 88 modern constellations today. Its name is Latin for twins, and it is associated with the twins Castor and Pollux in Greek mythology. Its old astronomical symbol is (♊︎).
7 Persei is a star in the constellation Perseus, located 774 light years away from the Sun. While the star bears the Bayer designation Chi Persei, it is not to be confused with the entire cluster NGC 884, commonly referred to as Chi Persei. It is faintly visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.99. This object is moving closer to the Earth with a heliocentric radial velocity of −12.5 km/s.
Perseus OB1 is an OB association in the Northern Celestial Hemisphere in the constellation Perseus. It is centered around the double cluster, and has lent its name to the Perseus Arm of the Milky Way. The brightest member of the association is the blue supergiant 9 Persei.
RS Persei is a red supergiant variable star located in the Double Cluster in Perseus. The star's apparent magnitude varies from 7.82 to 10.0, meaning it is never visible to the naked eye.
T Persei is a red supergiant located in the constellation Perseus. It varies in brightness between magnitudes 8.3 and 9.7 and is considered to be a member of the Double Cluster.
NGC 1545 is an open cluster in the constellation Perseus. It was discovered by William Herschel on December 28, 1790. It is located in the north-eastern part of the constellation, a few arcminutes east of the 4.5 magnitude star b Persei, near the equally large and bright NGC 1528, which is less than 1.5° towards the northwest. However, it is less dense and rich. The brightest star of the cluster is a K5 III giant star, with 7.1 magnitude, but its membership is questionable. One more 7.9 magnitude star is visible at the north edge of the cluster.
NGC 1245 is an open cluster in the constellation Perseus. It was discovered by William Herschel in 11 December 1786. It is located 3° southwest of alpha Persei and can be spotted with 10x50 binoculars. The cluster is nearly 1 billion years old. NGC 1245 has about 200 members the brightest of which are of 12th magnitude. The cluster shows evidence of mass segregation and it is possible that it has lost its lower mass members. Lying at a distance of 3kpc, the cluster is estimated to be 27 light years across.
V520 Persei is a blue supergiant member of NGC 869, one of the Perseus Double Cluster open clusters. It is an irregular variable star. At a magnitude of 6.55, V520 Persei is the brightest member in either NGC 869 or NGC 884, although the brighter HD 13994 lies in the foreground along the same line of sight.
NGC 1444 is a small open cluster of stars in the northern constellation of Perseus, about 2-1⁄4° to the northwest of 43 Persei. It has an angular diameter of 4 arcminutes and a brightness of 6.60 in visual magnitude. The cluster has sixty members of seventh magnitude or fainter, and is better appreciated in larger telescopes. NGC 1444 was discovered on 18 December 1788 by the German-British astronomer William Herschel. It is located at a distance of 4,200 light-years from the Sun and is about 7.1 million years old. The cluster has a physical core radius of 1.73 ± 0.42 ly and a tidal radius of 17.4 ± 4.2 ly. The most prominent member is the triple star system Σ446, with a magnitude 6.7 primary. The cluster is a member of the Camelopardalis OB1 association.
NGC 957 is a loosely bound open cluster located in the constellation Perseus. It has an apparent magnitude of 7.6 and an approximate size of 11 arc-minutes. It is young at less than 11 million years old.