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λ Cephei

Location of λ Cep (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cepheus
Right ascension	22 11 30.57571
Declination	+59° 24′ 52.15″
Apparent magnitude (V)	+5.050
Characteristics
Evolutionary stage	Blue supergiant
Spectral type	O6.5If(n)p
U−B color index	−0.622
B−V color index	+0.237
Astrometry
Radial velocity (Rv)	-75.10 km/s
Proper motion (μ)	RA: -7.46 mas/yr Dec.: -11.09 mas/yr
Parallax (π)	1.65 ± 0.22 mas
Distance	950 pc
Absolute magnitude (MV)	-6.43
Details
Mass	51.4 M☉
Radius	18 - 21 R☉
Luminosity	630,000 L☉
Surface gravity (log g)	3.54 cgs
Temperature	36,000 K
Rotation	210
Age	4.0 Myr
Other designations
Lambda Cephei, 22 Cephei, HD 210839, HR 8469, BD+58 2402, HIP 109556, SAO 34149, GSC 03981-01585, GC 31066
Database references
SIMBAD	data

Lambda Cephei (λ Cephei) is a fifth magnitude blue supergiant star in the constellation Cepheus, one of the hottest and most luminous visible to the naked eye.

Characteristics

It is a hot O6.5 supergiant star at a distance of approximately 1,980 light years, whose absolute brightness around half a million times the Sun. Its radius is around 20 times that of the latter, 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. Due to its very large initial mass, it will most likely leave behind 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.

References

1. ^ van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
2. ^ Bouret, J.-C.; Hillier, D. J.; Lanz, T.; Fullerton, A. W. (2012). "Properties of Galactic early-type O-supergiants. A combined FUV-UV and optical analysis". Astronomy & Astrophysics. 544: A67. arXiv:1205.3075. Bibcode:2012A&A...544A..67B. doi:10.1051/0004-6361/201118594. S2CID 119280104.
3. Sota, A.; Maíz Apellániz, J.; Walborn, N. R.; Alfaro, E. J.; Barbá, R. H.; Morrell, N. I.; Gamen, R. C.; Arias, J. I. (2011). "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R ~ 2500". The Astrophysical Journal Supplement Series. 193 (2): 24. arXiv:1101.4002. Bibcode:2011ApJS..193...24S. doi:10.1088/0067-0049/193/2/24. ISSN 0067-0049. S2CID 119248206.
4. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737. S2CID 119231169.
5. Bianchi, L.; Garcia, M. (2002). "The Effective Temperatures of Mid-O Stars". The Astrophysical Journal. 581 (1): 610–625. Bibcode:2002ApJ...581..610B. doi:10.1086/343042.
6. 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.
7. Gvaramadze, V. V.; Gualandris, A. (2011). "Very massive runaway stars from three-body encounters". Monthly Notices of the Royal Astronomical Society. 410 (1): 304–312. arXiv:1007.5057. Bibcode:2011MNRAS.410..304G. doi:10.1111/j.1365-2966.2010.17446.x. S2CID 123481910.

External links

• http://stars.astro.illinois.edu/Sow/lambdacep.html

v t e Constellation of Cepheus
List of stars in Cepheus Cepheus in Chinese astronomy
Stars	Bayer α (Alderamin) β (Alfirk) γ (Errai) δ ε ζ η θ ι κ λ μ (Garnet Star) ν ξ (Kurhah) ο π ρ ρ Flamsteed 7 9 11 14 16 19 24 2 UMi Variable AR T V W RW VV VW WZ DH DO MY PV S SS ST U V354 V381 V419 HR 597 881 7955 8281 8442 8702 8748 8938 9038 HD 1 197911 204521 Other Gliese 809 WISE 0313+7807 WR 156 IRAS 23077+6707
Exoplanets γ Cephei Ab (Tadmor) TOI-1431 b
Star clusters	NGC 188 6939 7023 7129 7142 7160 7380 7419 7429 7510 Other Palomar 1
Nebulae	NGC NGC 40 NGC 7129 NGC 7139 NGC 7354 NGC 7538 NGC 7822 Other Seahorse Nebula Elephant's Trunk Nebula Ghost Nebula Gyulbudaghian's Nebula IC 1396 Iris Nebula L1157 S 155 SSTGFLS J222557+601148
Galaxies	NGC 2276 2300 6952 Other 3C 61.1 S5 0014+81 NVSS 2146+82 UGC 11861
Category

• O-type supergiants
• Emission-line stars
• Runaway stars
• Cepheus (constellation)
• Durchmusterung objects
• Bayer objects
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects