Lambda Ceti

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Lambda Ceti, λ Cet
Cetus constellation map.svg
Lambda Ceti is the λ star in the Cetus constellation, just above Menkar (α Cet) in the pentangle.
Observation data
Epoch J2000      Equinox J2000
Constellation Cetus
Right ascension 02h 59m 42.900s[1]
Declination 08° 54′ 26.49″[1]
Apparent magnitude (V) 4.6767
Spectral type B6III[2]
U−B color index -0.45
B−V color index -0.12
Radial velocity (Rv) 10.2[2] km/s
Proper motion (μ) RA: 6.01 ± 0.26[1] mas/yr
Dec.: –17.70 ± 0.29[1] mas/yr
Parallax (π) 5.66 ± 0.24[1] mas
Distance 580 ± 20 ly
(177 ± 7 pc)
Absolute magnitude (MV) -1.56
Mass ~4.6[3] M
Radius 5.4[3] R
Luminosity 920[3] L
Temperature 13,940 ± 710[4] K
Rotational velocity (v sin i) 150[5] km/s
Age 100-125[3] Myr
Other designations
Menkar, λ Cet, 91 Cet, HR 896, BD +08° 455, HD 18604, FK5 1083, HIP 13954, SAO 110889
Database references
Exoplanet Archive data

Lambda Ceti (λ Cet, λ Ceti) is Class B star of fifth-magnitude star located in the constellation Cetus. Historically, the star bore the traditional name Menkar, although today that name is more commonly associated with α Ceti.

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".[6]

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, λ Ceti itself is known as 天囷三 (Tiān Qūn sān, English: the Third Star of Circular Celestial Granary.)[7]


Lambda Ceti is a blue giant star with stellar classification B6III. With a mass between 4.5-4.8 M and an estimated radius that is 5.4 R, the star radiates a bolometric luminosity of about 920 L.[3] In 1997 the Hipparcos satellite estimated its parallax at 7.69 ± 0.76 milliarcseconds yielding a distance from Earth of about 130 ± 10 parsecs or 420 ± 40 light years. However recent astrometric calculations by van Leeuwen have placed the distance much farther at about 177 ± 7 pc or 580 ± 20 ly—a revaluation which significantly altered other stellar parameters.[1] Its apparent magnitude has been recently recalibrated at 4.6767 yielding an absolute magnitude of -1.56, almost as bright as its neighbor Alpha Ceti at -1.62.

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