Lambda Cephei

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λ Cephei
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cepheus
Right ascension 22h 11m 30.5761s
Declination +59° 24′ 52″
Apparent magnitude (V) +5.08
Spectral type O6If(n)p
U−B color index -0.71
B−V color index 0.17
Radial velocity (Rv) -75 km/s
Proper motion (μ) RA: -7.46 mas/yr
Dec.: -11.09 mas/yr
Parallax (π) 1.65 ± 0.22 mas
Distance approx. 2,000 ly
(approx. 610 pc)
Absolute magnitude (MV) -6.40[1]
Mass 62[1] M
Radius 18[2]-21[1] R
Luminosity 400,000[2]-676,000[1] L
Surface gravity (log g) 3.5[2] cgs
Temperature 34,000[2]-36,000[1] K
Rotation 200[1]
Age 2.5[1] Myr
Other designations
Lambda Cephei, HD 210839, HR 8469
Database references

Lambda Cephei is a fifth magnitude star in the constellation Cepheus.


It's a hot supergiant O-type star at a distance of approximately 1,980 light years, whose absolute brightness around half a million times the Sun. Its radius is around 18 times that of our star, with a mass that has been estimated to be between 45 and 60 solar masses.

Lambda Cephei turns around its axis in less than three days compared to the 24.47 days that the Sun needs to complete a full rotation and seems to be single, with no companions. Its ultimate fate is to explode as a supernova leaving behind a neutron star or perhaps a black hole.

Lambda Cephei is also a runaway star that seems to have been expelled of the stellar association Cepheus OB3, that lies at 2,800 light-years, roughly 2,5 million years ago. Its motion through the interstellar medium is producing a shockwave in front of the gases that surround it and in the direction towards it moves.[3]

See also[edit]


  1. ^ a b c d e f g Repolust, T.; Puls, J.; Herrero, A. (2004). "Stellar and wind parameters of Galactic O-stars. The influence of line-blocking/blanketing". Astronomy and Astrophysics 415 (1): 349–376. Bibcode:2004A&A...415..349R. doi:10.1051/0004-6361:20034594.  edit
  2. ^ a b c d Bianchi, L.; Garcia, M. (2002). "The Effective Temperatures of Mid‐O Stars". The Astrophysical Journal 581: 610. doi:10.1086/343042.  edit
  3. ^ Gvaramadze, V. V.; Gualandris, A. (2011). "Very massive runaway stars from three-body encounters". Monthly Notices of the Royal Astronomical Society 410: 304. doi:10.1111/j.1365-2966.2010.17446.x.  edit

External links[edit]