Gamma Aquilae
 Location of γ Aquilae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 46m 15.58029s[1] |
| Declination | +10° 36′ 47.7408″[1] |
| Apparent magnitude (V) | 2.712[2] |
| Characteristics | |
| Spectral type | K3 II[3] |
| U−B color index | +1.720[2] |
| B−V color index | +1.500[2] |
| Astrometry | |
| Radial velocity (Rv) | -2.79[4] km/s |
| Proper motion (μ) | RA: +16.99[1] mas/yr Dec.: -2.98[1] mas/yr |
| Parallax (π) | 8.26 ± 0.17[1] mas |
| Distance | 395 ± 8 ly (121 ± 2 pc) |
| Absolute magnitude (MV) | −3.38+0.24 −0.22[5] |
| Details | |
| Mass | 5.66±0.66[6] M☉ |
| Radius | 95[7] R☉ |
| Luminosity | 2538[6] L☉ |
| Surface gravity (log g) | 1.63[8] cgs |
| Temperature | 4210[8] K |
| Metallicity [Fe/H] | –0.29[8] dex |
| Rotational velocity (v sin i) | 8[9] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Database references | |
| SIMBAD | data |
Gamma Aquilae (γ Aql, γ Aquilae) is a star in the constellation Aquila. It has the traditional name Tarazed.[11] This star has an apparent visual magnitude of 2.712,[2] so it is readily visible to the naked eye at night. Parallax measurements place it at a distance of 395 light-years (121 parsecs) from Earth.[1]
Properties
Gamma Aquilae is a relatively young star with an age of about 100 million years. Nevertheless, it has reached a stage of its evolution where it has consumed the hydrogen at its core and expanded into what is termed a bright giant star, with a stellar classification of K3 II.[3] The star is now burning helium into carbon in its core. After it has finished generating energy through nuclear fusion, Gamma Aquilae will become a white dwarf.[11]
The interferometry-measured angular diameter of Gamma Aquilae is 7.271±0.073 mas,[12] which, at its estimated distance, equates to a physical radius of about 95 times the radius of the Sun.[7] With almost six times the Sun's mass, this is an enormous star that is radiating over 2500 times the luminosity of the Sun.[6] An effective temperature of 4210 K in its outer envelope gives it the orange hue typical of K-type stars.[8][13]
In culture
The traditional name Tarazed may derive from Persian شاهين ترازو šāhin tarāzu "the beam of the scale", referring to an asterism of the Scale, α, β and γ Aquillae. Persian šāhīn means "royal falcon", "beam", and "pointer", and gave its name (as "falcon") to Beta Aquilae. In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Menkib al Nesr (منكب ألنسر - mankib al-nasr), which was translated into Latin as Humerus Vulturis, meaning the eagle's shoulder.[14]
In Chinese, 河鼓 (Hé Gŭ), meaning River Drum, refers to an asterism consisting of γ Aquilae, β Aquilae and Altair.[15] Consequently, γ Aquilae itself is known as 河鼓三 (Hé Gŭ sān, English: the Third Star of River Drum.)[16] In Chinese mythology, The Princess and the Cowherd, this star and β Aql, are children of Niulang (牛郎, The Cowherd, Altair) and Zhinü (織女, The Princess, Vega).
The Koori people of Victoria knew β and γ Aquilae as the black swan wives of Bunjil (Altair), the wedge-tailed eagle.[17]
References
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- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.. The radius (R*) is given by:
- ↑ 8.0 8.1 8.2 8.3 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ (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 978-986-7332-25-7.
- ↑ (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.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
