Lambda Velorum

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Lambda Velorum
Vela constellation map.svg
Red circle.svg

Location of λ Velorum (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vela
Right ascension 09h 07m 59.75787s[1]
Declination −43° 25′ 57.3273″[1]
Apparent magnitude (V) 2.21[2] (2.14 - 2.30[3]
Spectral type K4.5 Ib-II[4]
U−B color index +1.80[2]
B−V color index +1.65[2]
Variable type LC[3]
Radial velocity (Rv) +18.4[5] km/s
Proper motion (μ) RA: −24.01[1] mas/yr
Dec.: +13.52[1] mas/yr
Parallax (π) 5.99 ± 0.11[1] mas
Distance 545 ± 10 ly
(167 ± 3 pc)
Mass 8.5 ± 0.3[6] M
Radius 207[7] R
Luminosity 10,000[7] L
Surface gravity (log g) 1.4[8] cgs
Temperature 4,235[8] K
Metallicity [Fe/H] +0.23[8] dex
Age 31.6 ± 1.7[6] Myr
Other designations
Alsuhail, Al Suhail al Wazn, Suhail, Al' Sukhal', CD −42° 4990, FK5 345, HD 78647, HIP 44816, HR 3634, SAO 220878
Database references

Lambda Velorum (λ Vel or λ Velorum) is a star in the southern constellation of Vela. It has the traditional name Suhail, which, confusingly, is sometimes used for Gamma Velorum. With an mean apparent visual magnitude of 2.21,[2] this is the third brightest star in the constellation and one of the brighter stars in the sky. The distance to this star can be measured directly using the parallax technique, yielding an estimated 545 light-years (167 parsecs) from Earth.[1]

Lambda Velorum is an evolved star that is part way between the bright giant and supergiant stages, with a stellar classification of K4.5 Ib-II.[4] This star has exhausted the hydrogen in its core region and now generates part of its energy through the nuclear fusion of helium at the core. In the process, the star's outer envelope has expanded to form a deep, convective, hydrogen burning layer that is generating a magnetic field. The surface strength of this field has been measured at 1.72 ± 0.33 G.[4] It is an LC-type, slow irregular variable star with its brightness varying between apparent magnitudes +2.14 to +2.30.[3]

This star has about 8.5[6] times the mass of the Sun, placing it at the lower edge of the mass range where a star will end its life as a Type II supernova.[4] Massive stars use their hydrogen "fuel" much faster than do smaller stars and Lambda Velorum is estimated to be only some 32 million years old.[6] The outer envelope has an effective temperature of 4,235 K,[8] giving it the cool orange hue of a K-type star.[9]


The medieval name Suhail (Al Suhail, Alsuhail, Suhail Alwazn) is short for the Arabic السهيل الوزن suhayl al-wazn "The glorious (star) of the cycle". Sometimes also seen is Suhail (al) Muhlif, also used for Gamma Velorum.

In Chinese astronomy, Suhail is called 天記, Pinyin: Tiānjì, meaning Judge for Estimating the Age of Animals, because this star is marking itself and stand alone in Judge for Estimating the Age of Animals asterism, Ghost mansion (see : Chinese constellation).[10] 天記 (Tiānjì), westernized into Tseen Ke, but the name Tseen Ke was designated for ψ Vel by R. H. Allen works and the meaning is "Heaven's Record".[11]


  1. ^ a b c d e f 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 
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode:1966CoLPL...4...99J 
  3. ^ a b c Ruban, E. V.; et al. (September 2006), "=Spectrophotometric observations of variable stars", Astronomy Letters 32 (9): 604–607, Bibcode:2006AstL...32..604R, doi:10.1134/S1063773706090052 . See the J/PAZh/32/672 VizieR catalogue entry.
  4. ^ a b c d Grunhut, J. H.; et al. (November 2010), "Systematic detection of magnetic fields in massive, late-type supergiants", Monthly Notices of the Royal Astronomical Society 408 (4): 2290–2297, arXiv:1006.5891, Bibcode:2010MNRAS.408.2290G, doi:10.1111/j.1365-2966.2010.17275.x 
  5. ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. Bibcode:1953GCRV..C......0W. 
  6. ^ a b c d Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  7. ^ a b Kaler, James B., "SUHAIL (Lamda Velorum)", Stars (University of Illinois), retrieved 2012-02-17 
  8. ^ a b c d Luck, R. E. (September 1979), "The chemical compositions of nine southern supergiant stars", Astrophysical Journal, Part 1 232: 797–806, Bibcode:1979ApJ...232..797L, doi:10.1086/157340 
  9. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 
  10. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日
  11. ^ Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Argo Navis