Mu Cephei (μ Cep / μ Cephei) (also known as “Herschel’s pomegranate star”) is a red supergiant in the constellation Cepheus . One of the largest and most powerful (full luminosity 350,000 times higher than solar) stars in our Galaxy and belongs to the spectral class M2Ia.
| Mu Cepheus | |||
|---|---|---|---|
| Star | |||
 Comparative dimensions μ Cepheus and the Sun | |||
| Research history | |||
| Discoverer | William Herschel | ||
| opening date | 1780/1783 | ||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 5,255.12 St. years (1612.89 pc ) | ||
| Visible magnitude ( V ) | from +3.43 to +5.09 | ||
| Constellation | Cepheus | ||
| Astrometry | |||
| Radial velocity ( R v ) | +20.63 km / s | ||
| Own movement (μ) | RA: + 5.24 mas per year Dec: −2.88 mas per year | ||
| Parallax (π) | 0.62 mas | ||
| Absolute magnitude (V) | from −7.61 to −5.95 | ||
| Specifications | |||
| Spectral class | M2Ia | ||
| Color Index ( B - V ) | 2.26 | ||
| Color Index ( U - B ) | 2.42 | ||
| Variability | Src | ||
| physical characteristics | |||
| Weight | 25 M ☉ | ||
| Radius | 650 - 1420 R ☉ | ||
| Age | 11-12 Ma | ||
| Temperature | 2300 K | ||
| Luminosity | 350,000 L ☉ | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
Content
History
Mu Cephei's deep red color was noted by William Herschel : "... a very rich pomegranate color, the same as that of Omicron Whale " [1] . After his research, this star is often called the "Herschel pomegranate star" [2] . Giuseppe Piazzi cataloged it under the name Garnet Sidus (pomegranate constellation) [3] . In the mid-19th century, its variability was discovered by John Russell Hind at the Bishop Observatory . It is also called Erakis, apparently this is the erroneous name given by the Czech astronomer Antonín Bečvář in the atlas of 1951 , when he confused it with Mu Dragon , which has its own name Arrakis.
Properties
Mu Cephei is one of the largest and brightest stars; visible to the naked eye. In the northern hemisphere, the best observation time is from August to January.
A star is about 650 [4] - 1420 [5] times larger than the Sun (radius is 7.7 AU ) and if it were placed in its place, its circle would be between the orbits of Jupiter and Saturn . Mu Cepheus could contain a billion suns and 2.7 quadrillion lands . If the Earth were the size of a golf ball (4.3 cm), Mu Cephei would be the width of 2 Golden Gate bridges (5.5 km).
Mu Cephei is a semi - regular variable star of the SRc type, changing brightness in the range from 3.43 m to 5.1 m with a period of 2 to 2.5 years. V. Tsesevich managed to establish the periodicity of a complex curve of brightness changes; it is the result of adding three oscillations with periods of 90, 750, and 4675 days [6] . The reasons are erratic pulsations and non-periodic eruptions of hot gases from the bowels of the star into space.
Mu Cephei is 60 thousand times brighter than the Sun. Adding its apparent brightness, infrared radiation and stellar wind, we can calculate that its bolometric luminosity is 350,000 times greater than the solar.
In the scientific literature on the measurement of parallax , various estimates of the distance to the star from 390 to 1600 parsecs (from 1300 to 5200 light years ) are given, however, recently the upper estimate is generally accepted [7] . (5200 St. years ). She is also one of the coldest stars: the surface temperature is no more than 2300 K.
Mu Cephei is a dying star in the last stages of stellar evolution. She has already begun to burn helium , synthesizing carbon from it, while the stars in the main sequence burn hydrogen and synthesize helium from it. The helium-carbon cycle indicates that the star is completing its evolution and is likely to explode like a supernova within a few million years, and its massive core can collapse into a black hole .
Mu Cephei is a triple star; the main components of Mu Cephei B and Mu Cephei C have a visible magnitude of 12.3 m and 12.7 m and are located at an angular distance of 20.93 arc seconds and 42.68 arc seconds (respectively) from the main star.
Components
| Title | Right ascension | Declination | Apparent magnitude | Spectral class | Link |
|---|---|---|---|---|---|
| μ Cep B (CCDM J21435 + 5847B) | 21 h 43 m 27.8 s | + 58 ° 46 ′ 45 ″ | 12.3 m | M0 | Simbad |
| μ Cep C (CCDM J21435 + 5847C) | 21 h 43 m 25.6 s | + 58 ° 47 ′ 08 ″ | 12.7 m | A | Simbad |
continuation
| Title | Weight | Radius | Luminosity | Temperature | Rotation |
|---|---|---|---|---|---|
| μ Cep B | 2-5 M ☉ | 24 R ☉ | 36,58 L ☉ | 3850 K | 15.2 days |
| μ Cep C | ~ 2.5 M ☉ | ~ 2.5 R ☉ | 25,34 L ☉ | ~ 9000 K | 0.5 d |
See also
- List of the biggest stars
- List of the most massive stars.
- List of the brightest stars
- List of stars of the constellation Cepheus
Notes
- ↑ Herschel W., “Stars newly come to be visible,” Philosophical Transactions , the Royal Astronomical Society of London, 1783, p. 257.
- ↑ Allen RH, Star Names: Their Lore and Meaning | Star-Names and Their Meanings , G.. Stechert, 1899, p. 158.
- ↑ Piazzi, G., Palermo Catalog , 1814.
- ↑ Tsuji, Takashi. Water in Emission in the Infrared Space Observatory Spectrum of the Early M Supergiant Star μ Cephei (Eng.) // The Astrophysical Journal Letters: journal. - 2000. - Vol. 540 , no. 2 . - P. 99-102 . - DOI : 10.1086 / 312879 . - . - arXiv : astro-ph / 0008058 .
- ↑ Table 4 in Emily M. Levesque ; Philip Massey; KAG Olsen; Bertrand Plez; Eric Josselin; Andre Maeder; Georges Meynet. The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought (Eng.) // The Astrophysical Journal: journal. - 2005 .-- August ( vol. 628 , no. 2 ). - P. 973-985 . - DOI : 10.1086 / 430901 . - . - arXiv : astro-ph / 0504337 .
- ↑ Siegel F.Yu. Treasures of the Starry Sky: A Guide to Constellations and the Moon. - 5th ed. - M: Nauka , 1987 .-- S. 88. - 296 p.
- ↑ Perrin, G .; et al. Study of molecular layers in the atmosphere of the supergiant star µ Cep by interferometry in the K band // Astronomy & Astrophysics: journal. - 2005. - Vol. 436 . - P. 317-324 . - DOI : 10.1051 / 0004-6361: 20042313 .