Constellation | |
Abbreviation | Cep |
---|---|
Genitive | Cephei |
Pronunciation | /ˈsiːfiəs/ or /ˈsiːfjuːs/ ; genitive /ˈsiːfiaɪ/ |
Symbolism | the King/King Cepheus |
Right ascension | 20h 01m 56.4481s–09h 03m 19.7931s [1] |
Declination | 88.6638870°–53.3532715° [1] |
Area | 588 sq. deg. (27th) |
Main stars | 7 |
Bayer/Flamsteed stars | 43 |
Stars with planets | 1 |
Stars brighter than 3.00m | 1 |
Stars within 10.00 pc (32.62 ly) | 3 |
Brightest star | α Cep (Alderamin) (2.45 m ) |
Messier objects | 0 |
Meteor showers | 0 |
Bordering constellations | Cygnus Lacerta Cassiopeia Camelopardalis Draco Ursa Minor |
Visible at latitudes between +90° and −10°. Best visible at 21:00 (9 p.m.) during the month of November. |
Cepheus is a constellation in the far northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times.
The constellation's brightest star is Alpha Cephei, with an apparent magnitude of 2.5. Delta Cephei is the prototype of an important class of star known as a Cepheid variable. RW Cephei, an orange hypergiant, together with the red supergiants Mu Cephei, MY Cephei, VV Cephei, and V354 Cephei are among the largest stars known. In addition, Cepheus also has the hyperluminous quasar S5 0014+81, which hosts an ultramassive black hole in its core, reported at 40 billion solar masses, about 10,000 times more massive than the central black hole of the Milky Way, making this among the most massive black holes currently known. [2] [3]
Cepheus was the King of Aethiopia. He was married to Cassiopeia and was the father of Andromeda, both of whom are immortalized as modern day constellations along with Cepheus. [4]
Alpha Cephei, also known as Alderamin, is the brightest star in the constellation, with an apparent magnitude of 2.51. [5] Gamma Cephei, also known as Errai, is the second-brightest star in the constellation, with an apparent magnitude of 3.21. [6] It is a binary star, made up by a orange giant or subgiant [7] and a red dwarf. [8] The primary component hosts one exoplanet, Gamma Cephei Ab (Tadmor). [9] Delta Cephei is a yellow-hued supergiant star 980 light-years from Earth and the prototype of the class of the Cepheid variables. It was discovered to be variable by John Goodricke in 1784. It varies between 3.5 m and 4.4m over a period of 5 days and 9 hours. The Cepheids are a class of pulsating variable stars; Delta Cephei has a minimum size of 40 solar diameters and a maximum size of 46 solar diameters. It is also a double star; the primary star also has a wide-set blue-hued companion of magnitude 6.3. [10]
There are three red supergiants in the constellation that are visible to the naked eye. Mu Cephei, also is known as Herschel's Garnet Star due to its deep red colour. It is a semiregular variable star with a minimum magnitude of 5.1 and a maximum magnitude of 3.4. Its period is approximately 2 years. [11] The star is around 5.64 AU in radius. If it were placed at the center of the Solar System, it would extend to the orbit of Jupiter. Another, VV Cephei A, like Mu Cephei, is a red supergiant and a semiregular variable star, located at least 5,000 light-years from Earth. It has a minimum magnitude of 5.4 and a maximum magnitude of 4.8, and is paired with a blue main sequence star called VV Cephei B. One of the largest stars in the galaxy, it has a diameter exceeding a thousand times that of the Sun. [11] VV Cephei is also an unusually long-period eclipsing binary, but the eclipses, which occur every 20.3 years, are too faint to be observed with the unaided eye. The third, Zeta Cephei, is not as large as Mu Cephei and VV Cephei with a diameter only 94 times that of the Sun (comparable to the orbit of Mercury), [12] and has an apparent magnitude of 3.35. [13]
There are several prominent double stars and binary stars in Cepheus. Omicron Cephei is a binary star with a period of 800 years. The system, 211 light-years from Earth, consists of an orange-hued giant primary of magnitude 4.9 and a secondary of magnitude 7.1. Xi Cephei is another binary star, 102 light-years from Earth, with a period of 4,000 years. It has a blue-white primary of magnitude 4.4 and a yellow secondary of magnitude 6.5. [11]
Kruger 60 is an 11th-magnitude binary star consisting of two red dwarfs. The star system is one of the nearest, being only 13 light-years away from Earth.
Cepheus is most commonly depicted as holding his arms aloft, praying for the deities to spare the life of Andromeda. He also is depicted as a more regal monarch sitting on his throne. [4]
In Chinese astronomy, the stars of the constellation Cepheus are found in two areas: the Purple Forbidden enclosure (紫微垣, Zǐ Wēi Yuán) and the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ).
Antlia is a constellation in the Southern Celestial Hemisphere. Its name means "pump" in Latin and Greek; it represents an air pump. Originally Antlia Pneumatica, the constellation was established by Nicolas-Louis de Lacaille in the 18th century. Its non-specific (single-word) name, already in limited use, was preferred by John Herschel then welcomed by the astronomic community which officially accepted this. North of stars forming some of the sails of the ship Argo Navis, Antlia is completely visible from latitudes south of 49 degrees north.
Ara is a southern constellation between Scorpius, Telescopium, Triangulum Australe, and Norma. It was one of the Greek bulk described by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations designated by the International Astronomical Union.
Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to Canis Minor, the "lesser dog"; both figures are commonly represented as following the constellation of Orion the hunter through the sky. The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41.
Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.
Grus is a constellation in the southern sky. Its name is Latin for the crane, a type of bird. It is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-centimetre-diameter (14-inch) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas-Louis de Lacaille gave Bayer designations to its stars in 1756, some of which had been previously considered part of the neighbouring constellation Piscis Austrinus. The constellations Grus, Pavo, Phoenix and Tucana are collectively known as the "Southern Birds".
Telescopium is a minor constellation in the southern celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is a Latinized form of the Greek word for telescope. Telescopium was later much reduced in size by Francis Baily and Benjamin Gould.
Ursa Minor, also known as the Little Bear, is a constellation located in the far northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the North American name, Little Dipper: seven stars with four in its bowl like its partner the Big Dipper. Ursa Minor was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Ursa Minor has traditionally been important for navigation, particularly by mariners, because of Polaris being the north pole star.
Norma is a small constellation in the Southern Celestial Hemisphere between Ara and Lupus, one of twelve drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenter's square, a set square or a level. It remains one of the 88 modern constellations.
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.
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille. Its name is Latin for compass, referring to the drafting tool used for drawing circles. Its brightest star is Alpha Circini, with an apparent magnitude of 3.19. Slightly variable, it is the brightest rapidly oscillating Ap star in the night sky. AX Circini is a Cepheid variable visible with the unaided eye, and BX Circini is a faint star thought to have been formed from the merger of two white dwarfs. Two sun-like stars have planetary systems: HD 134060 has two small planets, and HD 129445 has a Jupiter-like planet. Supernova SN 185 appeared in Circinus in 185 AD and was recorded by Chinese observers. Two novae have been observed more recently, in the 20th century.
Musca is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe 35 cm (14 in) in diameter published in 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. It was also known as Apis for 200 years. Musca remains below the horizon for most Northern Hemisphere observers.
Aquila is a constellation on the celestial equator. Its name is Latin for 'eagle' and it represents the bird that carried Zeus/Jupiter's thunderbolts in Greek-Roman mythology.
Mu Cephei, also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified.
VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus, approximately 5,000 light years from Earth. It is both a B[e] star and shell star.
Nu Cephei is a class A2, fourth-magnitude supergiant star in the constellation Cepheus. It is a white pulsating α Cygni variable star located about 4,700 light-years from Earth.
V381 Cephei is a triple star system in the northern constellation of Cepheus. Its apparent magnitude is slightly variable between 5.5 and 5.7.
KQ Puppis is a spectroscopic binary variable star in the constellation Puppis. A red supergiant star and a hot main sequence star orbit each other every 9,742 days. Its apparent magnitude varies between 4.82 and 5.17.
U Lacertae is a spectroscopic binary star in the constellation Lacerta.
NGC 7419 is an open cluster in the constellation Cepheus. It is heavily reddened and notable for containing five red supergiants, the highest number known in any cluster until the end of the 20th century, but probably no blue supergiants.