Epsilon Carinae

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Epsilon Carinae A/B
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]
Characteristics
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]
Astrometry
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)
Details
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
SIMBAD data

Epsilon Carinae (ε Car, ε Carinae) is a star in the southern constellation of Carina. It is also known by the name Avior. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from the northern hemisphere.

Illustration of the Avior system

Epsilon Carinae is a double star located roughly 560–660 light-years (170–200 parsecs) away from the Earth.[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.[11] This pair may form an eclipsing binary system[11] with a period of 785 days (2.15 years), resulting in a magnitude change of 0.12 during each eclipse.[6][12]

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]

Etymology[edit]

The name Avior is not a classical in origin. It was assigned to the star by Her Majesty's 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".[13]

In Chinese, 海石 (Hǎi Dàn), meaning Sea Rock, refers to an asterism consisting of ε Carinae, ι Carinae, HD 83183, HD 84810 and υ Carinae .[14] Consequently, ε Carinae itself is known as 海石一 (Hǎi Dàn yī, English: the First Star of Sea Rock.)[15]

References[edit]

  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:0708.1752, 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), 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 1, Ann Arbor: Dept. of Astronomy, University of Michigan, 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), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, 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:1007.4883, 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. ^ a b Kaler, James B., "AVIOR (Epsilon Carinae)", Stars (University of Illinois), retrieved 2012-02-12. 
  12. ^ 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 
  13. ^ Safler, D. H., Wilkins, G. A., ed., A Personal History of H.M. Nautical Almanac Office (PDF), Sidford, Devon: Unpublished, p. 4. 
  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 978-986-7332-25-7.
  15. ^ (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.