MU CEPHEI

'Mu Cephei' (μ Cep / μ Cephei), also known as '''Garnet Sidus''', is a Red supergiant star in the constellation Cepheus.

Contents

History

Properties

See also

External links

History

It was named Garnet Sidus by Giuseppe Piazzi in his ''Palermo Catalogue'' of stars, from Herschel's comment for some stars not listed in Flamsteed's '''British Catalogue''' of stars, in 1783 edition of the '''Philosophical transactions'''. There Sir William Herschel noted one of which was "a very fine deep garnet colour, such as the periodical star ο ceti". It appears garnet red due to its spectral class of M2Ia. Garnet Sidus is more popularly known as "Herschel's '''Garnet Star'''". An alternative name '''Erakis''' in Bečvář's star catalogue is probably confused μ Cep with μ Dra. Mu Draconis had previously called '''al-Rāqis''' [ar-rá:qis] in Arabic.

Properties

A very luminous red supergiant, Mu Cephei is one of the largest and brightest stars visible not only to the naked eye but in the entire Galaxy. It is best seen from the Northern hemisphere from August to January.
The star is approximately 1,420 times larger than our sun's solar radius, and if it were placed in the Sun's position, its radius would reach between the orbits of Jupiter and Saturn. Mu Cephei could fit over 1 billion suns into its body. Only five known stars (VY Canis Majoris, KW Sagitarii, KY Cygni, V354 Cephei and VV Cephei) are believed to be larger than it.
Mu Cephei is a variable star and the prototype of the class of the Mu Cephei variables. Its apparent brightness varies without recognizable pattern between +3.62 mag and +5 mag in a period of 2 to 2.5 years. Mu Cephei is 38,000 times brighter than the Sun, with an absolute visible magnitude of M_''v'' = −7.0. Combining its absolute visible brightness, its infrared radiation and its interstellar extinction gives a luminosity of around 350,000 solar luminosities, making it one of the most luminous stars known. It is approximately 3,000 light years away from the Sun.
Mu Cephei is now in the dying stage of stars. It has begun to fuse helium into carbon, whereas a "healthy" main sequence star fuses hydrogen into helium. The helium-carbon cycle shows that Mu Cephei is in the last phase of its life and is possibly about to go supernova (in astronomical terms, of course: at least some million years). When a star goes supernova it is destroyed, leaving behind a vast hydrogen cloud which, for a star as massive as Mu Cephei, may be centered on a black hole.

See also

★ List of largest stars

External links

★ HD 206936

★ The Garnet Star from Jim Kaler's '' Stars''.

★ AAVSO: Star of the Month from AAVSO: ''Variable Star of the Month'', Mu Cephei

★ Mu Cephei a grand red star