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Orion constellation map.svg
Red circle.svg

λ (circled) in the constellation Orion.
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 35m 08.27761s[1]
Declination +09° 56′ 02.9611″[1]
Apparent magnitude (V) 3.33 (3.50 + 5.45)[2]
Spectral type O8 III((f))[3]
U−B color index –1.01[4]
B−V color index –0.21[4]
Spectral type B0.5 V[4]
U−B color index –0.77[4]
B−V color index +0.04[4]
Radial velocity (Rv) +30.10[5] km/s
Proper motion (μ) RA: –0.34[1] mas/yr
Dec.: –2.94[1] mas/yr
Parallax (π) 2.97 ± 0.55[1] mas
Distance approx. 1,100 ly
(approx. 340 pc)
Absolute magnitude (MV) –4.25 / -1.94
Mass 27.9 ± 3.3[6] M
Radius 10.0[7] R
Luminosity 165,000[4] L
Surface gravity (log g) 43.90[8] cgs
Temperature 37,689[8] K
Metallicity [Fe/H] 0.03[8] dex
Mass 10.3 ± 0.7[9] M
Radius 4.2 ± 0.8[9] R
Luminosity 6,300[9] L
Surface gravity (log g) 4.21 ± 0.10[9] cgs
Temperature 25,400 ± 500[9] K
Age 1.8[9] Myr
Other designations
λ Orionis, 39 Orionis, 101 G. Orionis, BD+09°879, HIP 26207, SAO 112921
A: HD 36861, HR 1879
B: HD 36862, HR 1880
Database references

Meissa, designated Lambda Orionis (λ Orionis, abbreviated Lambda Ori, λ Ori) is a star in the constellation of Orion.


Meissa, just north of blue φ1 and yellow φ2 Orionis

Lambda Orionis is the star's Bayer designation. The traditional name Meissa derives from the Arabic Al-Maisan which means 'The Shining One'. This term was also used for Gamma Gemini (Alhena), but was somehow mistakenly applied to Lambda Orionis and the name stuck. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[11] included a table of the first two batches of names approved by the WGSN; which included Meissa for this star. It is now so entered in the IAU Catalog of Star Names.[12]

The original Arabic name for this star, Al Hakah (the source for another name for it, Heka) refers to the Arabic lunar mansion that includes this star and the two of Phi Orionis (Al Haḳʽah, 'a White Spot').[13] In Chinese, 觜宿 (Zī Sù), meaning Turtle Beak, refers to an asterism consisting of Meissa and both of Phi Orionis[14] Consequently, Meissa itself is known as 觜宿一 (Zī Sù yī, English: the First Star of Turtle Beak.)[15]


Meissa is a giant star with a stellar classification of O8 III and an apparent visible magnitude 3.54.[4] It is an enormous star with about 28[6] times the mass of the Sun and 10 times the Sun's radius.[7] The outer atmosphere has an effective temperature of around 35,000 K,[7] giving it the characteristic blue glow of a hot O-type star.[16] Meissa is a soft X-ray source with a luminosity of 1032 erg s−1 and peak emission in the energy range of 0.2–0.3 keV, which suggests the X-rays are probably being generated by the stellar wind.[17]

Meissa is actually a double star with a companion at an angular separation of 4.41 arcseconds along a position angle of 43.12° (as of 1937).[18] This fainter component is of magnitude 5.61 and it has a stellar classification of B0.5 V,[4] making it a B-type main sequence star. There is an outlying component, Meissa C, which is an F-type main sequence star with a classification of F8 V. This star in turn may have a very low mass companion that is probably a brown dwarf.[17]


WISE infrared view of the ring around Meissa

Meissa is surrounded by a ring of nebulosity about 30 degrees across. It is thought to be the remains of a supernova explosion, now ionised by the ultraviolet radiation from Meissa itself and some of the surrounding hot stars.[19]


This star is the dominant member of a 5-million-year-old star-forming region known as the λ Orionis cluster,[20] or Collinder 69. The intense ultraviolet energy being radiated by this star is creating the Sh2-264[21] H II region in the neighboring volume of space, which in turn is surrounded by an expanding ring of cool gas that has an age of about 2–6 million years. The expansion of this gaseous ring may be explained by a former binary companion of Meissa that became a Type II supernova. Such an event would also explain the star's peculiar velocity with respect to the center of the expanding ring, as the explosion and resulting mass loss could have kicked Meissa out of the system. A potential candidate for the supernova remnant is the neutron star Geminga.[22] However, the last is unlikely given the distance between Geminga and the cluster.[23]


  1. ^ a b c d e van Leeuwen, F. (November 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 
  2. ^ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869. arXiv:0806.2878Freely accessible. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. 
  3. ^ Sota, A.; Maíz Apellániz, J.; Walborn, N. R.; Alfaro, E. J.; Barbá, R. H.; Morrell, N. I.; Gamen, R. C.; Arias, J. I. (2011). "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-violet at R ~ 2500". The Astrophysical Journal Supplement. 193 (2): 24. arXiv:1101.4002Freely accessible. Bibcode:2011ApJS..193...24S. doi:10.1088/0067-0049/193/2/24. 
  4. ^ a b c d e f g h Murdin, P.; Penston, M. V. (December 1977), "The Lambda Orionis association", Monthly Notices of the Royal Astronomical Society, 181 (4): 657–665, Bibcode:1977MNRAS.181..657M, doi:10.1093/mnras/181.4.657 
  5. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  6. ^ a b 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:1007.4883Freely accessible, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  7. ^ a b c Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601 
  8. ^ a b c Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2011). "Coudé-feed stellar spectral library - atmospheric parameters". Astronomy and Astrophysics. 525: A71. arXiv:1009.1491Freely accessible. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. 
  9. ^ a b c d e f Lyubimkov, Leonid S.; Rachkovskaya, Tamara M.; Rostopchin, Sergey I.; Lambert, David L. (2002). "Surface abundances of light elements for a large sample of early B-type stars - II. Basic parameters of 107 stars". Monthly Notices of the Royal Astronomical Society. 333: 9. Bibcode:2002MNRAS.333....9L. doi:10.1046/j.1365-8711.2002.05341.x. 
  10. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. 
  11. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016. 
  12. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  13. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 318, ISBN 0486210790, retrieved 2011-07-16 
  14. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 9789867332257.
  15. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 24 日
  16. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  17. ^ a b Franciosini, E.; Sacco, G. G. (June 2011), "XMM-Newton observations of the young open cluster around λ Orionis", Astronomy & Astrophysics, 530: A150, arXiv:1104.3803Freely accessible, Bibcode:2011A&A...530A.150F, doi:10.1051/0004-6361/201015248 
  18. ^ Scardia, M. (September 1983), "Micrometric measurements of binary stars (first list)", Astronomy and Astrophysics Supplement Series (in French), 53: 433–440, Bibcode:1983A&AS...53..433S 
  19. ^ Koenig, Xavier; Hillenbrand, Lynne A.; Padgett, Deborah L.; Defelippis, Daniel (2015). "SPECTROSCOPIC ASSESSMENT OFWISE-BASED YOUNG STELLAR OBJECT SELECTION NEARλANDσORIONIS". The Astronomical Journal. 150 (4): 100. doi:10.1088/0004-6256/150/4/100. 
  20. ^ Bouy, H.; et al. (September 2009), "A deep look into the core of young clusters. II. λ-Orionis", Astronomy and Astrophysics, 504 (1): 199–209, arXiv:0907.0322Freely accessible, Bibcode:2009A&A...504..199B, doi:10.1051/0004-6361/200912569 
  21. ^ Barrado Y Navascués, D. (December 2005). "Lambda Orionis Star Forming Region: toward a comprehensive study of the stellar and substellar population". In Hidalgo-Gámez, A. M.; González, J. J.; Espinosa, J. M. Rodríguez; Torres-Peimbert, S. II International GTC Workshop: Science with GTC 1st-light Instruments and the LMT. Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias). 24. pp. 217–218. Bibcode:2005RMxAC..24..217B. 
  22. ^ Cunha, K.; Smith, V. V. (May 1996), "Is the expanding molecular cloud surrounding λ Orionis caused by a Supernova?", Astronomy and Astrophysics, 309: 892–894, Bibcode:1996A&A...309..892C 
  23. ^ Pellizza, L. J.; et al. (May 2005), "On the local birth place of Geminga", Astronomy and Astrophysics, 435 (2): 625–630, arXiv:astro-ph/0502190Freely accessible, Bibcode:2005A&A...435..625P, doi:10.1051/0004-6361:20042377