Lambda Boötis

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Lambda Boötis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Boötes
Right ascension 14h 16m 23.019s[1]
Declination +46° 05′ 17.90″[1]
Apparent magnitude (V) +4.18
Spectral type A0p
Proper motion (μ) RA: −187.33±0.14[1] mas/yr
Dec.: 159.05±0.11[1] mas/yr
Parallax (π) 32.94 ± 0.16[1] mas
Distance 99.0 ± 0.5 ly
(30.4 ± 0.1 pc)
Mass 1.66+0.19
[2] M
Radius 1.7[3] R
Luminosity 19.1+9.0
[2] L
Surface gravity (log g) 4.188[4] cgs
Temperature 8720[5] K
Rotational velocity (v sin i) 100[4] km/s
Age 2.8+1.1
[2] Gyr
Other designations
19 Boötis, HR 5351, HD 125162, GJ 3837, BD+46°1949, FK5 527, HIP 69732, SAO 44965, GC 19273.
Database references

Lambda Boötis (λ Boo, λ Boötis) is a star in the constellation Boötes.

Lambda Boötis is a white A-type main sequence dwarf with an apparent magnitude of +4.18. It is approximately 99 light-years from Earth. Lambda Boötis is the prototype of a group of rare stars known as Lambda Boötis stars, all of which are dwarf stars with unusually low abundances of metals in their spectra. Its diameter has been directly measured to be 1.7 times that of the Sun.[3]


This star, along with the Aselli (θ Boo, ι Boo and κ Boo), were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas".[6]

Al Aulād al Dhiʼbah or Aulad al Thiba was the title of this star in the catalogue of stars in Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars.[7]

In Chinese astronomy, Lambda Boötis is called 玄戈, Pinyin: Xuángē, meaning Sombre Lance, because this star is marking itself and stand alone in Sombre Lance asterism, Purple Forbidden enclosure (see : Chinese constellation).[8] 玄戈 (Xuángē) westernized into Heuen Ko, but the name Heuen Ko was designated for γ Boötis (Seginus) by R.H. Allen, with the meaning is "the heavenly spear" [9]


  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c Montesinos, B.; et al. (March 2009), "Parameters of Herbig Ae/Be and Vega-type stars", Astronomy and Astrophysics, 495 (3): 901–917, arXiv:0811.3557Freely accessible, Bibcode:2009A&A...495..901M, doi:10.1051/0004-6361:200810623 
  3. ^ a b Ciardi; et al. (2007), "The Angular Diameter of λ Boötis", The Astrophysical Journal, 659 (2): 1623–1628, arXiv:astro-ph/0612723Freely accessible, Bibcode:2007ApJ...659.1623C, doi:10.1086/512077 
  4. ^ a b Song, Inseok; Caillault, J.-P.; Barrado y Navascués, David; Stauffer, John R. (February 2001), "Ages of A-Type Vega-like Stars from uvbyβ Photometry", The Astrophysical Journal, 546 (1): 352–357, arXiv:astro-ph/0010102Freely accessible, Bibcode:2001ApJ...546..352S, doi:10.1086/318269 
  5. ^ Martínez-Galarza, J. R.; et al. (March 2009), "Infrared Emission by Dust Around λ Bootis Stars: Debris Disks or Thermally Emitting Nebulae?", The Astrophysical Journal, 694 (1): 165–173, arXiv:0812.2198Freely accessible, Bibcode:2009ApJ...694..165M, doi:10.1088/0004-637X/694/1/165 
  6. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 105, ISBN 0-486-21079-0, retrieved 2010-12-12 
  7. ^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
  8. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 14 日
  9. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Boötes

External links[edit]