Eta Canis Majoris

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η Canis Majoris
Location of η Canis Majoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 07h 24m 05.70228s[1]
Declination –29° 18′ 11.1798″[1]
Apparent magnitude (V) 2.450[2]
Characteristics
Spectral type B5 Ia[3]
U−B color index −0.708[2]
B−V color index −0.087[2]
Variable type α Cyg[4]
Distance
approx. 2,000 ly
(approx. 600 pc)
Absolute magnitude (MV)−7.0[6]
Details
Myr
HIP 35904, HR 2827, SAO
 173651
Database references
SIMBADdata

Eta Canis Majoris (η Canis Majoris, abbreviated Eta CMa, η CMa), also named Aludra

spectrum of this star has served as one of the stable anchor points by which other stars are classified.[11]

Nomenclature

η Canis Majoris (Latinised to Eta Canis Majoris) is the star's Bayer designation.

The traditional name Aludra originates from the

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 Aludra for this star.

In

HD 65456, Omicron Puppis, k Puppis, Epsilon Canis Majoris, Kappa Canis Majoris and Pi Puppis. Consequently, Eta Canis Majoris itself is known as 弧矢二 (Hú Shǐ èr, English: the Second Star of Bow and Arrow).[16]

Properties

A light curve for Eta Canis Majoris, plotted from Hipparcos data[17]

A blue-white

spectral type of B5Ia.[18]

Eta CMa shines brightly in the skies in spite of a large distance from Earth due to being intrinsically many times brighter than the Sun. It has a luminosity over 100,000 times and a radius around 54 times that of the Sun. It has only been around a fraction of the time the Sun has, less than 10 million years, yet is already in the last stages of its life. It is still expanding and may become a red supergiant, or perhaps has already passed that phase, but in either case it will become a supernova within the next few million years.[citation needed]

Eta CMa is classified as an Alpha Cygni-type variable star and its brightness varies from magnitude +2.38 to +2.48 over a period of 4.7 days.[4][19]

Namesakes

Both

U.S. Navy
vessels named after the star.

References

  1. ^
    S2CID 18759600
    .
  2. ^
    doi:10.1086/150019
  3. S2CID 59151633
  4. ^
    Bibcode:1999IBVS.4659....1K
    .
  5. Bibcode:1999VeARI..35....1W
  6. doi:10.1093/mnras/189.3.601
  7. S2CID 237605138
    .
  8. ^
    S2CID 126150688
    .
  9. S2CID 118629873
    .
  10. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  11. Bibcode:1993AAS...183.1710G, archived from the original
    on 2019-06-25, retrieved 2012-02-04
  12. ISBN 0-486-21079-0
    , retrieved 2010-12-12
  13. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  14. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  15. ^ 弧矢 (Hú Shǐ) is westernized into Koo She. R.H. Allen had opinion that Koo She refers to the asterism including Delta Velorum and Omega Velorum. AEEA opinion is, Delta Velorum is member of 天社 (Tiān Shè), meaning Celestial Earth God's Temple asterism, and Omega Velorum is not member of any asterisms. 天社 (Tiān Shè) is westernized into Tseen She and R.H. Allen used the term Tseen She for Chinese name of Eta Carinae. See Richard Hinckley Allen: Star Names — Their Lore and Meaning: Argo Navis and (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日 Archived 2012-02-04 at the Wayback Machine.
  16. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日 Archived 2012-02-04 at the Wayback Machine
  17. ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 12 August 2022.
  18. Bibcode:1978rmsa.book.....M.{{cite book}}: CS1 maint: location missing publisher (link
    )
  19. ^ Watson, Christopher (3 May 2013). "Eta Canis Majoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 5 February 2014.
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