Eta Aquilae
 Location of Eta Aquilae to the left of center |
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| Observation data Epoch J2000 Equinox J2000 |
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|---|---|
| Constellation | Aquila |
| Right ascension | 19h 52m 28.3679s |
| Declination | +01° 00′ 20.378″ |
| Apparent magnitude (V) | 3.5 to 4.4[1] |
| Characteristics | |
| Spectral type | F6Iab |
| U−B color index | 0.51 |
| B−V color index | 0.89 |
| R−I color index | 0.47 |
| Variable type | Cepheid variable[1] |
| Astrometry | |
| Radial velocity (Rv) | -14.8 km/s |
| Proper motion (μ) | RA: 6.94 mas/yr Dec.: -7.3 mas/yr |
| Parallax (π) | 2.78 ± 0.91 mas |
| Distance | approx. 1,200 ly (approx. 400 pc) |
| Details | |
| Mass | 7 M☉ |
| Radius | 107 ± 11[2] R☉ |
| Luminosity | 3,400 L☉ |
| Temperature | 5,300–6,200 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
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Eta Aquilae (η Aql, η Aquilae) is a star in the constellation Aquila. It was also part of the former constellation Antinous. It is a Cepheid variable star, varying from apparent magnitude 3.5 to 4.4 with a period of 7.176641 days.[1] Along with Delta Cephei, Zeta Geminorum and Beta Doradus, it is one of the most prominent naked eye Cepheids[citation needed]; that is, both the star itself and the variation in its brightness can be distinguished by the naked eye. Some other Cepheids such as Polaris are bright but have only a very small variation in brightness.
It is about 1200 light years from Earth.[citation needed] It is a yellow-white supergiant, and is about 3000 times more luminous than the Sun, with a diameter about 60 times that of the Sun.[citation needed]
[edit] Name
Sometimes, this star is called by the name Bezek, derived the Hebrew word בֶזֶק bazak, meaning "lightning".[3]
In Chinese, 天桴 (Tiān Fú), meaning Celestial Drumstick, refers to an asterism consisting of η Aquilae, θ Aquilae, 62 Aquilae and 58 Aquilae.[4] Consequently, η Aquilae itself is known as 天桴四 (Tiān Fú sì, English: the Fourth Star of Celestial Drumstrick.)[5]
This star, along with δ Aql (Denebokab) and θ Aql (Tseen Foo) and, were Al Mizān (ألميزان), the Scale-beam.[6] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Mizān were the title for three stars :δ Aql as Al Mizān I,η Aql as Al Mizān II and θ Aql as Al Mizān III[7]
[edit] References
- ^ a b c "GCVS Query=eta Aql". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. http://www.sai.msu.su/gcvs/cgi-bin/search.cgi?search=eta+Aql. Retrieved 2010-11-24.
- ^ Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032–3038, Bibcode 1999AJ....118.3032N, doi:10.1086/301114
- ^ (Turkish) YILDIZ ADLARI SÖZLÜĞÜ - Mustafa Pultar (Bezek)
- ^ (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) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日
- ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 61. ISBN 0486210790. http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Aquila*.html. Retrieved 2010-12-12.
- ^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
[edit] External links
- "HD 187929 -- Classical Cepheid (Delta Cep Type)". SIMBAD Astronomical Database. http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=eta+aquilae. Retrieved 2007-01-21.
- Eta Aquilae
- Image Eta Aquilae
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