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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 08.27608s[1]
Declination +09° 56′ 02.9913″[1]
Apparent magnitude (V) 3.7[2]
Right ascension 05h 35m 08.48130s[3]
Declination +09° 56′ 06.0995″[3]
Apparent magnitude (V) 5.6[2]
Spectral type O8 III((f))[4]
U−B color index −1.01[5]
B−V color index −0.21[5]
Spectral type B0 V[5]
U−B color index −0.77[5]
B−V color index +0.04[5]
Radial velocity (Rv)+30.10[6] km/s
Proper motion (μ) RA: +2.896[1] mas/yr
Dec.: −3.183[1] mas/yr
Parallax (π)2.5936 ± 0.4032 mas[1]
Distanceapprox. 1,300 ly
(approx. 390 pc)
Absolute magnitude (MV)−4.25
Proper motion (μ) RA: +2.216[3] mas/yr
Dec.: −1.986[3] mas/yr
Parallax (π)2.4682 ± 0.1543 mas[3]
Distance1,320 ± 80 ly
(410 ± 30 pc)
Absolute magnitude (MV)−1.94
Mass27.9±3.3[7] M
Radius13.4[8] R
Luminosity165,000[5] L
Surface gravity (log g)3.90[9] cgs
Temperature35,000[8] K
Metallicity [Fe/H]0.03[9] dex
Mass10.3±0.7[10] M
Radius4.2±0.8[10] R
Luminosity6,300[10] L
Surface gravity (log g)4.21±0.10[10] cgs
Temperature25,400±500[10] K
Age1.8[10] 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 /ˈmsə/, designated Lambda Orionis (λ Orionis, abbreviated Lambda Ori, λ Ori) is a star in the constellation of Orion. It is a multiple star approximately 1,300 ly away with a combined apparent magnitude of 3.33.[11] The main components are an O8 giant star and a B-class main sequence star, separated by about 4″. Despite Meissa being more luminous and only slightly further away than Rigel, it appears 3 magnitudes dimmer at visual wavelengths, with much of its radiation emitted in the ultraviolet due to its high temperature.


Meissa with nebulosity north of 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'. Al-Maisan was originally used for Gamma Geminorum, but was mistakenly applied to Lambda Orionis and the name stuck.[12] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[14] 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.[15]

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').[12] In Chinese, 觜宿 (Zī Sù), meaning Turtle Beak, refers to an asterism consisting of Meissa and both of Phi Orionis[16] Consequently, the Chinese name for Meissa itself is 觜宿一 (Zī Sù yī, English: the First Star of Turtle Beak.)[17]


Meissa is a giant star with a stellar classification of O8 III and an apparent visible magnitude 3.54. It is an enormous star with about 26[8]-28[7] times the mass of the Sun and 10[18]-13 [8] times the Sun's radius. The outer atmosphere has an effective temperature of around 35,000 K,[18] [8] giving it the characteristic blue glow of a hot O-type star.[19] 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.[20] The stellar wind of Meissa is well characterized by a mass-loss rate of 2.5×10−8 solar masses per year and a terminal velocity of 2,000 km/s.[8]

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).[21] This fainter component is of magnitude 5.61 and it has a stellar classification of B0 V, 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.[20]


WISE infrared view of the ring around Meissa, which is the faint "white" star north of the small bright red nebula.

Meissa is surrounded by a ring of nebulosity about 12 degrees across. It is thought to be the remains of a supernova explosion, now ionized by the ultraviolet radiation from Meissa itself and some of the surrounding hot stars.[22]


This star is the dominant member of a 5-million-year-old star-forming region known as the λ Orionis cluster,[23] or Collinder 69. The intense ultraviolet energy being radiated by this star is creating the Sh2-264[24] 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.[25] However, the last is unlikely given the distance between Geminga and the cluster.[26]



  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b Melnik, A. M.; Dambis, A. K. (April 2020). "Internal motions in OB associations with Gaia DR2". Monthly Notices of the Royal Astronomical Society. 493 (2): 2339–2351. arXiv:2002.05044. Bibcode:2020MNRAS.493.2339M. doi:10.1093/mnras/staa454.
  3. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  4. ^ 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:1101.4002. Bibcode:2011ApJS..193...24S. doi:10.1088/0067-0049/193/2/24. S2CID 119248206.
  5. ^ a b c d e f 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.
  6. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
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  9. ^ a b 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:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. S2CID 53480665.
  10. ^ 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 (1): 9–26. Bibcode:2002MNRAS.333....9L. doi:10.1046/j.1365-8711.2002.05341.x.
  11. ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue ofStellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
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  13. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
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  16. ^ (in 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.
  17. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 24 日
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