Eta Canis Majoris
Eta Canis Majoris
|
Eta Canis Majoris, a blue Supergiant in Canis Major
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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 |
| Astrometry |
|
| Radial velocity (Rv) |
41.1[4] km/s |
| Proper motion (μ) |
RA: -4.14[1] mas/yr
Dec.: 5.81[1] mas/yr |
| Parallax (π) |
1.64 ± 0.40[1] mas |
| Distance |
approx. 2000 ly
(approx. 600 pc) |
|
| Details |
|
| Mass |
19.19 ± 1.15[5] M☉ |
| Luminosity |
105,442[5] L☉ |
| Temperature |
15,000[3] K |
| Rotational velocity (v sin i) |
50[6] km/s |
|
| Other designations |
Aludra, 31 Canis Majoris, HR 2827, CD−29°4328, HD 58350, SAO 173651, FK5 283, HIP 35904, GC 9886, CCDM 07240-2918 |
| Database references |
| SIMBAD |
data |
Eta Canis Majoris (η CMa, η Canis Majoris) is a star in the constellation Canis Major. It has the traditional name Aludra.
The name Aludra originates from the Arabic: عذرا al-‘aðrā "the virgin". This star, along with ε CMa (Adhara), δ CMa (Wezen) and ο2 CMa (Thanih al Adzari), were Al ʽAdhārā (ألعذاري), the Virgins.[7]
In Chinese, 弧矢 (Hú Shǐ), meaning Bow and Arrow,[8] refers to an asterism consisting of η Canis Majoris, δ Canis Majoris, c Puppis, ZI 674, ο Puppis, κ Puppis, ε Canis Majoris, κ Canis Majoris and π Puppis.[9] Consequently, δ Canis Majoris itself is known as 弧矢二 (Hú Shǐ èr, English: the Second Star of Bow and Arrow.)[10]
Properties
Aludra shines brightly in the skies in spite of a large distance from Earth due to being intrinsically many times brighter (absolute magnitude) than the Sun. A blue supergiant, Aludra has only been around a fraction of the time our Sun has, 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.
η Canis Majoris is classified as an Alpha Cygni type variable star and its brightness varies from magnitude +2.38 to +2.48.
Namesakes
Both USS Aludra (AF-55) and USS Aludra (AK-72), a Crater class cargo ship, were United States Navy vessels named after the constellation.
References
- ^ a b c d e van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. Bibcode 2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ^ a b c Alcaino, Gonzalo (June 1969), "The Globular Clusters NGC 2808 and NGC 1851", Astrophysical Journal 156: 853, Bibcode 1969ApJ...156..853A, doi:10.1086/150019
- ^ a b Prinja, R. K.; Massa, D. L. (October 2010), "Signature of wide-spread clumping in B supergiant winds", Astronomy and Astrophysics 521, Bibcode 2010A&A...521L..55P, doi:10.1051/0004-6361/201015252
- ^ Wielen, R. et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, Astronomisches Rechen-Institut Heidelberg, Bibcode 1999VeARI..35....1W
- ^ a b Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, Bibcode 2010AN....331..349H, doi:10.1002/asna.200911355
- ^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1 pages=359–365), Bibcode 2002ApJ...573..359A, doi:10.1086/340590
- ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 130, ISBN 0486210790, http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Canis_Major*.html, retrieved 2010-12-12
- ^ 弧矢 (Hú Shǐ) is westernized into Koo She. R.H. Allen had opinion that Koo She refers to the asterism including δ Velorum and ω Velorum. AEEA opinion is, δ Velorum is member of 天社 (Tiān Shè), meaning Celestial Earth God's Temple asterism and ω 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 η Carinae. See Richard Hinckley Allen: Star Names — Their Lore and Meaning: Argo Navis and (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日.
- ^ (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.
- ^ (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.