Lambda Cephei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 11m 30.577s[1] |
| Declination | +59° 24′ 52.154″[1] |
| Apparent magnitude (V) | +5.050[2] |
| Characteristics | |
| Evolutionary stage | Blue supergiant |
| Spectral type | O6.5If(n)p[3] |
| U−B color index | −0.622[2] |
| B−V color index | +0.237[2] |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | −75.10[4] km/s |
| Proper motion (μ) | RA: −7.020 mas/yr[1] Dec.: −10.812 mas/yr[1] |
| Parallax (π) | 1.1761±0.0818 mas[1] |
| Distance | 2,800 ± 200 ly (850 ± 60 pc) |
| Absolute magnitude (MV) | −6.43+0.11 −0.12[2] |
| Details[2] | |
| Mass | 51.4+15.2 −12.0 M☉ |
| Radius | 18[5] – 21[6] R☉ |
| Luminosity | 630,000 L☉ |
| Surface gravity (log g) | 3.54 cgs |
| Temperature | 36,000 K |
| Rotational velocity (v sin i) | 210 km/s |
| Age | 4.0±0.2 Myr |
| Other designations | |
| Lambda Cephei, 22 Cephei, NSV 14069, BD+58 2402, GC 31066, HD 210839, HIP 109556, HR 8469, SAO 34149, GSC 03981-01585[7] | |
| Database references | |
| SIMBAD | data |
Lambda Cephei is a blue supergiant star in the northern constellation of Cepheus. Its name is a Bayer designation that is Latinized from λ Cephei, and is abbreviated Lambda Cep or λ Cep. This star is visible to the naked eye with an apparent visual magnitude of +5.050.[2] Based on parallax measurements, it is located at a distance of approximately 2,800 light years.[1] It is one of the hottest and most luminous stars visible to the naked eye.
Characteristics
It is a hot O6.5 supergiant star, with an absolute brightness around half a million times that of the Sun and a radius around 20 times as big, and 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 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.[8]
References
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e f Bouret, J.-C.; et al. (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.
- ^ Sota, A.; et al. (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.
- ^ 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.
- ^ 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.
- ^ Repolust, T.; et al. (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.
- ^ "lam Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-01-29.
- ^ 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.