Astronomy:Lambda Velorum

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Short description: Evolved K-type star in the constellation of Vela
λ Velorum
(Suhail)
Vela constellation map.svg
Red circle.svg
Location of λ Velorum (circled)
Observation data
Equinox J2000.0]] (ICRS)
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])
Characteristics
Spectral type K4 Ib[4]
U−B color index +1.80[2]
B−V color index +1.65[2]
Variable type LC[3]
Astrometry
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
Distance545 ± 10 ly
(167 ± 3 pc)
Absolute magnitude (MV)−3.99[6]
Details
Mass7 ± 1[7] M☉
Radius210[7] R☉
Luminosity7,900[7] L☉
Surface gravity (log g)0.6[7] cgs
Temperature3,800–4,000[7] K
Metallicity [Fe/H]+0.06[8] dex
Rotational velocity (v sin i)6.7[6] km/s
Age31.6 ± 1.7[9] 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
SIMBADdata

Lambda Velorum (λ Velorum, abbreviated Lambda Vel, λ Vel), officially named Suhail /ˈsuːheɪl/,[10] is a star in the southern constellation of Vela. With a 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 the Sun.[1]

Nomenclature

λ Velorum (Latinised to Lambda Velorum) is the star's Bayer designation.

It bore the traditional Arabic name السهيل الوزن suhayl al-wazn (Al Suhail al Wazn), but as a modern navigation star this was shortened to Suhail. 'Suhail' (a common Arabic male first name) was traditionally used for at least three other stars: Canopus; Gamma Velorum (al Suhail al Muhlif); and Zeta Puppis (Suhail Hadar). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalogue and standardize proper names for stars. The WGSN approved the name Suhail for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names (Canopus had its name approved as is, and Zeta Puppis was given the name Naos).[10]

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 stands alone in the Judge for Estimating the Age of Animals asterism. Ghost mansion (see: Chinese constellation),[12] 天記 (Tiānjì), was westernized into Tseen Ke, but the name Tseen Ke was designated for Psi Velorum by R. H. Allen works and the meaning is "Heaven's Record".[13]

Properties

A light curve for Lambda Velorum, plotted from Hipparcos data[14]

The outer envelope of λ Velorum has an effective temperature of about 4,000 K, giving it the cool orange hue of a K-type star.[15] It is an Lc-type, slow irregular variable star with its brightness varying between apparent magnitudes +2.14 to +2.30.[3]

λ Velorum is an evolved star that has exhausted the hydrogen in its core region. It has about seven times the mass of the Sun. It is likely to be on or approaching the asymptotic giant branch (AGB), although its properties do not exclude it being a slightly more massive star on the red giant branch (RGB).[16] As an AGB star it has an inert core of carbon and oxygen and is alternately fusing helium and hydrogen in two shells outside the core. 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.[17] 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.[9]

λ Velorum is near the upper end of the mass range for intermediate stars, which end their lives by producing a planetary nebula and a white dwarf remnant. It may be massive enough to produce an electron-capture supernova.[18]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  2. ↑ 2.0 2.1 2.2 2.3 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. ↑ 3.0 3.1 3.2 Ruban, E. V. et al. (September 2006), "Spectrophotometric observations of variable stars", Astronomy Letters 32 (9): 604–607, doi:10.1134/S1063773706090052, Bibcode: 2006AstL...32..604R . See the J/PAZh/32/672 VizieR catalogue entry.
  4. ↑ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K. 
  5. ↑ Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Carnegie Institute of Washington D.C.). Bibcode: 1953GCRV..C......0W. 
  6. ↑ 6.0 6.1 Setiawan, J.; Pasquini, L.; Da Silva, L.; Hatzes, A. P.; von Der Lühe, O.; Girardi, L.; De Medeiros, J. R.; Guenther, E. (2004). "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch". Astronomy and Astrophysics 421: 241. doi:10.1051/0004-6361:20041042-1. Bibcode: 2004A&A...421..241S. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Carpenter, Kenneth G.; Robinson, Richard D.; Harper, Graham M.; Bennett, Philip D.; Brown, Alexander; Mullan, Dermott J. (1999). "GHRS Observations of Cool, Low-Gravity Stars. V. The Outer Atmosphere and Wind of the Nearby K Supergiant λ Velorum". The Astrophysical Journal 521 (1): 382–406. doi:10.1086/307520. Bibcode: 1999ApJ...521..382C. 
  8. ↑ Luck, R. Earle (2014). "Parameters and Abundances in Luminous Stars". The Astronomical Journal 147 (6): 137. doi:10.1088/0004-6256/147/6/137. Bibcode: 2014AJ....147..137L. 
  9. ↑ 9.0 9.1 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, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode: 2011MNRAS.410..190T 
  10. ↑ 10.0 10.1 "IAU Catalog of Star Names". http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt. 
  11. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016. 
  12. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日
  13. ↑ Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Argo Navis, https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Argo_Navis*.html 
  14. ↑ "Hipparcos Tools Interactive Data Access". ESA. https://www.cosmos.esa.int/web/hipparcos/interactive-data-access. 
  15. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16 
  16. ↑ Carpenter, Kenneth G. (1998). "The Structure of the Outer Atmosphere and Wind of lambda Vel". Asymptotic Giant Branch Stars 191: P206. Bibcode: 1998IAUS..191P.206C. 
  17. ↑ 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, doi:10.1111/j.1365-2966.2010.17275.x, Bibcode: 2010MNRAS.408.2290G 
  18. ↑ Nomoto, K. (1984). "Evolution of 8-10 solar mass stars toward electron capture supernovae. I - Formation of electron-degenerate O + NE + MG cores". Astrophysical Journal 277: 791. doi:10.1086/161749. Bibcode: 1984ApJ...277..791N. 



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