Lambda Ceti
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 02h 59m 42.893s[2] |
| Declination | +08° 54′ 26.589″[2] |
| Apparent magnitude (V) | 4.71[1] |
| Characteristics | |
| Spectral type | B6III[3] |
| U−B color index | −0.471[1] |
| B−V color index | −0.109±0.006[1] |
| Astrometry | |
| Radial velocity (Rv) | 10.2±2.8[4] km/s |
| Proper motion (μ) | RA: 8.382 mas/yr[2] Dec.: −16.385 mas/yr[2] |
| Parallax (π) | 7.3207±0.1451 mas[2] |
| Distance | 446 ± 9 ly (137 ± 3 pc) |
| Absolute magnitude (MV) | −1.52[1] |
| Details | |
| Mass | 5.01±0.05[5] M☉ |
| Radius | 5.4[6] R☉ |
| Luminosity | 652[1] L☉ |
| Temperature | 13,940±710[7] K |
| Rotational velocity (v sin i) | 131[8] km/s |
| Age | 100-125[6] Myr |
| Other designations | |
| Menkar, λ Cet, 91 Cet, BD+08°455, FK5 1083, HD 18604, HIP 13954, HR 896, SAO 110889[9] | |
| Database references | |
| SIMBAD | data |
Lambda Ceti is a star in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from λ Ceti, and abbreviated Lambda Cet or λ Cet. Historically, the star bore the traditional name Menkar, although today that name is more commonly associated with α Ceti. With an apparent visual magnitude of 4.71,[1] it is faintly visible to the naked eye. Based on parallax measurement of 7.32 mas as seen from Earth, it is located at a distance of approximately 446 light-years (137 pc) from the Sun. The star is drifting further away with a line of sight velocity component of 10 km/s.[4]
This star, along with α Cet (Menkar), γ Cet (Kaffaljidhma), δ Cet, μ Cet, ξ1 Cet and ξ2 Cet were Al Kaff al Jidhmah, "the Part of a Hand".[10]
In Chinese, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of λ Ceti, α Ceti, κ1 Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, δ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for λ Ceti itself is 天囷三 (Tiān Qūn sān, English: the Third Star of Circular Celestial Granary.)[11]
Lambda Ceti is a blue giant star with stellar classification B6III. It is an estimated 100-125 million years old,[6] and is spinning rapidly with a projected rotational velocity of 131 km/s.[8] It has five[5] times the mass of the Sun and 5.4 times the Sun's radius. The star is radiating 920[6] times the Sun's luminosity at an effective temperature of 13,940 K.[7]
References
- ^ a b c d e f g Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015 XHIP record for this object at VizieR.
- ^ a b c d 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.
- ^ Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179.
- ^ a b Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
- ^ a b Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
- ^ a b c d Kaler, James B., "LAMBDA CET (Lambda Ceti, the former "Menkar")", Stars, University of Illinois, retrieved 2010-09-30.
- ^ a b Zorec, J.; et al. (2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics, 501 (1): 297–320, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147, S2CID 14969137.
- ^ a b Simón-Díaz, S.; et al. (January 2017), "The IACOB project. III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars", Astronomy & Astrophysics, 597: 17, arXiv:1608.05508, Bibcode:2017A&A...597A..22S, doi:10.1051/0004-6361/201628541, S2CID 3478126, A22.
- ^ "lam Cet", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2010-09-30
- ^ Allen, R. H., "Cetus, the Whale or Sea Monster", Star Name, p. 160, retrieved 2026-02-24.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日 Archived 2012-02-04 at the Wayback Machine