Eta Aquilae
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Star η Aquilae |
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| AladinLite | |||||||||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Eagle | ||||||||||||||||||||
| Right ascension | 19 h 52 m 28.37 s | ||||||||||||||||||||
| declination | + 01 ° 00 ′ 20.4 ″ | ||||||||||||||||||||
| Apparent brightness | 3.48 mag to 4.39 mag | ||||||||||||||||||||
| Typing | |||||||||||||||||||||
| B − V color index | +0.89 | ||||||||||||||||||||
| U − B color index | +0.51 | ||||||||||||||||||||
| R − I index | +0.47 | ||||||||||||||||||||
| Spectral class | F6 Ib to G4 Ib | ||||||||||||||||||||
| Variable star type | Delta Cephei | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | (−25.1 ± 0.2) km / s | ||||||||||||||||||||
| distance | 1,200 ly 360 pc |
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| Proper movement | |||||||||||||||||||||
| Rec. Share: | (6.91 ± 1.47) mas / a | ||||||||||||||||||||
| Dec. portion: | (−8.21 ± 1.04) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Dimensions | 7 M ☉ | ||||||||||||||||||||
| radius | 60 R ☉ | ||||||||||||||||||||
| Luminosity |
3400 L ☉ |
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| Effective temperature | 5300 to 6200 K | ||||||||||||||||||||
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Other names and catalog entries |
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Eta Aquilae (η Aql) is a supergiant about 1200 light-years from Earth in the constellation Eagle , 8 ° south of the lighter Altair . But it also represented the head of the ancient (no longer recognized) constellation Antinous , through whose creation the young deceased, darling of the same name of the Roman emperor Hadrian was honored. Very rarely Eta Aquilae is also referred to by its Hebrew name Bezek or Bazak (meaning lightning ).
As a Cepheid variable, the apparent magnitude of Eta Aquilae varies between +3.48 mag and +4.39 mag with a period of 7.17 days. Together with Delta Cephei , Zeta Geminorum and Beta Doradus , Eta Aquilae is one of the brightest Cepheids, whose fluctuations in brightness were discovered by Edward Pigott as early as 1784 and which can be observed with the naked eye, while the likewise bright Pole Star, for example, has too little differences between maximum and minimum having. From the period-luminosity relationship one can calculate the distance from Eta Aquilae to be 1100 light years; this value therefore agrees very well with the value of 1200 light years calculated from the measured parallax.
literature
- The Brockhaus. Astronomy . 2006, p. 15.