Epsilon Carinae

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Epsilon Carinae
Diagram showing star positions and boundaries of the Carina constellation and its surroundings
Cercle rouge 100%.svg

Location of ε Carinae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension 08h 22m 30.83526s[1]
Declination −59° 30′ 34.1431″[1]
Apparent magnitude (V) 1.86[2] (2.166/4.121)[3]
Spectral type K3 III[4] + B2 Vp[5]
U−B color index +0.19[2]
B−V color index +1.27[2]
Variable type Eclipsing (suspected)[6]
Radial velocity (Rv) +11.6[7] km/s
Proper motion (μ) RA: –25.52[1] mas/yr
Dec.: 22.72[1] mas/yr
Parallax (π) 5.39 ± 0.42[1] mas
Distance 610 ± 50 ly
(190 ± 10 pc)
ε Car A
Mass 9.0 ± 0.9[8] M
Temperature 3,523[9] K
Age 31.2 ± 10.1[8] Myr
ε Car B
Mass 7.30[9] M
Temperature 20,417[9] K
Other designations
Avior, CD−59°1032, FK5 315, HD 71129, HIP 41037, HR 3307, SAO 235932.[10]
Database references

Epsilon Carinae (ε Carinae, abbreviated Epsilon Car, ε Car), also named Avior,[11] is a binary star in the southern constellation of Carina. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from the northern hemisphere. The False Cross is an asterism formed of Delta Velorum, Kappa Velorum, Iota Carinae and ε Carinae. It is so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation.[12]

Illustration of the Avior system

Epsilon Carinae is located roughly 560–660 light-years (170–200 parsecs) from the Sun.[1] Measurements during the Hipparcos mission give the pair an angular separation of 0.46 arcseconds with a difference in magnitude of 2.0.[5] At their estimated distance, this angle is equivalent to a physical separation of around 4 astronomical units.[13] This pair may form an eclipsing binary system[13] with a period of 785 days (2.15 years), resulting in a magnitude change of 0.12 during each eclipse.[6][14]

The primary component has an apparent visual magnitude of 2.2,[3] which by itself would still make it the third-brightest star in the constellation. It is an evolved giant star with a stellar classification of K0 III. However, examination of the ultraviolet flux from this star suggests it may instead be of spectral type K7.[5] The fainter secondary companion has an apparent visual magnitude of 4.1,[3] which, if it were a solitary star, would be bright enough to be seen with the naked eye. This is a hot, core hydrogen-fusing B-type main sequence star of spectral class B2 Vp.[5] The secondary may itself have an orbiting stellar companion of spectral class F8.[9]


ε Carinae (Latinised to Epsilon Carinae) is the star's Bayer designation.

The name Avior is not classical in origin. It was assigned to the star by HM Nautical Almanac Office in the late 1930s during the creation of The Air Almanac, a navigational almanac for the Royal Air Force. Of the fifty-seven navigation stars included in the new almanac, two had no classical names: Epsilon Carinae and Alpha Pavonis. The RAF insisted that all of the stars must have names, so new names were invented. Alpha Pavonis was named "Peacock", a translation of Pavo, whilst Epsilon Carinae was called "Avior".[15] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[17] included a table of the first two batches of names approved by the WGSN; which included Avior for this star.

In Chinese, 海石 (Hǎi Dàn), meaning Sea Rock, refers to an asterism consisting of ε Carinae, Iota Carinae, HD 83183, HD 84810 and Upsilon Carinae .[18] Consequently, ε Carinae itself is known as 海石一 (Hǎi Dàn yī, English: the First Star of Sea Rock.)[19]


  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:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c 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 Fabricius, C.; Makarov, V. V. (April 2000), "Two-colour photometry for 9473 components of close Hipparcos double and multiple stars", Astronomy and Astrophysics, 356: 141–145, Bibcode:2000A&A...356..141F. 
  4. ^ Houk, Nancy (1978), "Michigan catalogue of two-dimensional spectral types for the HD stars", University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0, Ann Arbor: Dept. of Astronomy, University of Michigan, 1, Bibcode:1975mcts.book.....H. 
  5. ^ a b c d Parsons, Sidney B.; Ake, Thomas B. (November 1998), "Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample", The Astrophysical Journal Supplement Series, 119 (1): 83–104, Bibcode:1998ApJS..119...83P, doi:10.1086/313152. 
  6. ^ a b Hoffleit, Dorrit; Warren Jr, W. H., The Bright Star Catalogue (5th revised ed.), Smithsonian Astrophysical Observatory, retrieved 2012-02-12. . See: VizieR V/50
  7. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, University of Toronto: International Astronomical Union, 30: 57, Bibcode:1967IAUS...30...57E. 
  8. ^ 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:1007.4883free to read, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x. 
  9. ^ a b c d Parsons, Sidney B. (May 2004), "New and Confirmed Triple Systems with Luminous Cool Primaries and Hot Companions", The Astronomical Journal, 127 (5): 2915–2930, Bibcode:2004AJ....127.2915P, doi:10.1086/383546. 
  10. ^ "eps Car -- Double or multiple star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-02-12. 
  11. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  12. ^ Moore, Patrick (2010). Patrick Moore's Astronomy: Teach Yourself. Hachette. ISBN 1444129775. 
  13. ^ a b Kaler, James B., "AVIOR (Epsilon Carinae)", Stars, University of Illinois, retrieved 2012-02-12. 
  14. ^ Hoffleit, Dorrit (1996), "A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars", The Journal of the American Association of Variable Star Observers, 24 (2): 105–116, Bibcode:1996JAVSO..24..105H 
  15. ^ Safler, D. H., Wilkins, G. A., ed., A Personal History of H.M. Nautical Almanac Office (PDF), Sidford, Devon: Unpublished, p. 4. 
  16. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. 
  17. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016. 
  18. ^ (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 978-986-7332-25-7.
  19. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.