Mu Cephei

Not to be confused with MY Cephei.
μ Cephei
Location of μ Cep (circled)
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] or 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]
Distance2,090 – 3,060 ly
(641+148
−144[11]–940+140
−40[12] pc)
Absolute magnitude (MV)–7.63[13]
Details
Mass25[14] M☉
Radius972±228[11] or 1,259[15] – 1,420[13] R☉
Luminosity269,000+111,000
−40,000[12] (135,000[11] – 340,000[13]) L☉
Surface gravity (log g)–0.36[15][14] cgs
Temperature3,750[15] K
Age10.0±0.1[16] Myr
Other designations
Erakis, Herschel's Garnet Star, μ Cep, HD 206936, HR 8316, BD+58°2316, HIP 107259, SAO 33693
Database references
SIMBADdata

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.

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.

  1. ^ a b Cite error: The named reference aaa323_L49 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference aaass34_1 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference jay was invoked but never defined (see the help page).
  5. ^ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. S2CID 123149047.
  6. ^ Cite error: The named reference shenavrin was invoked but never defined (see the help page).
  7. ^ a b Garrison, Robert F.; Kormendy, John (1976). "Some Characteristics of the Young Open Cluster Trumpler 37". Publications of the Astronomical Society of the Pacific. 88 (526): 865–869. Bibcode:1976PASP...88..865G. doi:10.1086/130037. ISSN 0004-6280. JSTOR 40676037.
  8. ^ Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference dr2 was invoked but never defined (see the help page).
  10. ^ Hipparcos, the New Reduction (van Leeuwen, 2007)
  11. ^ a b c Cite error: The named reference montargès was invoked but never defined (see the help page).
  12. ^ a b Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS. 493 (1): 468–476. arXiv:2001.06020. Bibcode:2020MNRAS.493..468D. doi:10.1093/mnras/staa174. S2CID 210714093.
  13. ^ a b c Cite error: The named reference levesqueetal2005 was invoked but never defined (see the help page).
  14. ^ a b Cite error: The named reference ariste was invoked but never defined (see the help page).
  15. ^ a b c Cite error: The named reference josselin was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference mnras410_1_190 was invoked but never defined (see the help page).