Mu Cephei
Red supergiant star in the constellation Cepheus / From Wikipedia, the free encyclopedia
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Mu Cephei (Latinized from μ Cephei, abbreviated Mu Cep or μ Cep), also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant[4][7] 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.
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cepheus |
Right ascension | 21h 43m 30.4609s[1] |
Declination | +58° 46′ 48.166″[1] |
Apparent magnitude (V) | +4.08[2] (3.43 - 5.1[3]) |
Characteristics | |
Evolutionary stage | Red supergiant or hypergiant[4] |
Spectral type | M2-Ia[5] (M2e Ia[6]) (M2 Ia+)[7] |
U−B color index | +2.42[2] |
B−V color index | +2.35[2] |
Variable type | SRc[3] |
Astrometry | |
Radial velocity (Rv) | +20.63[8] km/s |
Proper motion (μ) | RA: 2.740±0.884[9] mas/yr Dec.: −5.941±0.922[9] mas/yr |
Parallax (π) | 0.55 ± 0.20 mas[10] |
Distance | 3,060 ly (940+140 −40[11] pc) |
Absolute magnitude (MV) | –7.63[12] |
Details | |
Mass | 19.2±0.1[13] M☉ |
Radius | 972±228[14] (1,259[15] – 1,420[12])[16] R☉ |
Luminosity | 269,000+111,000 −40,000[11] (135,000[14] – 340,000[12]) L☉ |
Surface gravity (log g) | –0.36[15] – –0.5[12] cgs |
Temperature | 3,551±136[14] (3,750[15] – 3,700[12])[16] K |
Age | 10.0±0.1[13] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Mu Cephei is more than 100,000 times brighter than the Sun, with an absolute visual magnitude of −7.6. It is also one of the largest known stars with a radius around or over 1,000 times that of the sun (R☉), and were it placed in the Sun's position it would engulf the orbit of Mars and Jupiter.