Zeta Aquilae
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Star ζ Aquilae |
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| Aquila constellation | |||||||||||||||||||
| AladinLite | |||||||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Eagle | ||||||||||||||||||
| Right ascension | 19 h 05 m 24.61 s | ||||||||||||||||||
| declination | + 13 ° 51 ′ 48.5 ″ | ||||||||||||||||||
| Apparent brightness | 2.99 likes | ||||||||||||||||||
| Typing | |||||||||||||||||||
| B − V color index | +0.01 | ||||||||||||||||||
| U − B color index | −0.09 | ||||||||||||||||||
| R − I index | +0.00 | ||||||||||||||||||
| Spectral class | A0 Vn | ||||||||||||||||||
| Astrometry | |||||||||||||||||||
| Radial velocity | (−25.0 ± 4.0) km / s | ||||||||||||||||||
| parallax | (39.28 ± 0.16) mas | ||||||||||||||||||
| distance | (83.03 ± 0.34) Lj (25.46 ± 0.10) pc |
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| Visual absolute brightness M vis | approx. +1.0 mag | ||||||||||||||||||
| Proper movement | |||||||||||||||||||
| Rec. Share: | (−7.25 ± 0.15) mas / a | ||||||||||||||||||
| Dec. portion: | (−95.56 ± 0.12) mas / a | ||||||||||||||||||
| Physical Properties | |||||||||||||||||||
| Dimensions | 2.55 M ☉ | ||||||||||||||||||
| radius | 2.2 R ☉ | ||||||||||||||||||
| Luminosity |
123 L ☉ |
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| Effective temperature | 9700 K | ||||||||||||||||||
| Rotation time | 16 hours | ||||||||||||||||||
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Other names and catalog entries |
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ζ Aquilae ( Zeta Aquilae , short ζ Aql ) is a star in the constellation of eagle .
Zeta Aquilae is the third brightest star in the constellation Eagle after Alpha Aql ( Altair ) and Gamma Aql ( Tarazed ). It is a main sequence star of the spectral class A0 and has an apparent magnitude of 2.99 mag. Its distance is about 83 light years . It rotates unusually fast at about 165 times the speed of the sun. From this its rotation time is calculated to be only about 16 hours, which shows it as a very young star.
Zeta Aquilae has two faint companions, probably of the spectral class M. The closer one is about 12.0 mag bright and 6.5 arc seconds away from the main component, so that it needs at least 800 years for one orbit. The outer companion is about 11.8 mag bright and 159 arc seconds away from the main star; however, it could also just be an optical double star , i.e., seen from the earth, it could only be close to the main component by chance.
The star bears the historical proper name Deneb el Okab Australis (from Arabic ذنب العقاب, DMG ḏanab al-ʿuqāb 'Tail of the Eagle'). The star Epsilon Aquilae is distinguished from Zeta Aquilae with the proper name Deneb el Okab Borealis . His proper name, as determined by the IAU, is Okab .