Iota Aquilae
 Location of ι Aquilae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 36m 43.27606s[1] |
| Declination | –01° 17′ 11.7611″[1] |
| Apparent magnitude (V) | 4.364[2] |
| Characteristics | |
| Spectral type | B5 III[3] |
| U−B color index | –0.428[2] |
| B−V color index | –0.083[2] |
| R−I color index | –0.08 |
| Astrometry | |
| Radial velocity (Rv) | –21.4[4] km/s |
| Proper motion (μ) | RA: –0.87[1] mas/yr Dec.: –20.39[1] mas/yr |
| Parallax (π) | 8.34 ± 0.79[1] mas |
| Distance | 390 ± 40 ly (120 ± 10 pc) |
| Details | |
| Mass | 4.8 ± 0.3[5] M☉ |
| Radius | 5.5 ± 0.5[5] R☉ |
| Luminosity | 851[5] L☉ |
| Surface gravity (log g) | 3.64 ± 0.05[5] cgs |
| Temperature | 14,552[6] K |
| Rotational velocity (v sin i) | 55[7] km/s |
| Age | 100 ± 8[5] Myr |
| Other designations | |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) |
|
Iota Aquilae (ι Aql, ι Aquilae) is the Bayer designation for a star in the equatorial constellation of Aquila. It has the traditional name Al Thalimain, which it shares with λ Aquilae. The name is derived from the Arabic term الظليمان ath-thalīmain meaning "The Two Ostriches". With an apparent visual magnitude of 4.364,[2] this star is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 8.34 ± 0.79 mas,[1] it is located at a distance of around 390 light-years (120 parsecs) from Earth. At that distance, the visual magnitude of the star is diminished by 0.15[5] from extinction caused by intervening gas and dust.
In Chinese, 右旗 (Yòu Qí), meaning Right Flag, refers to an asterism consisting of ι Aquilae, μ Aquilae, σ Aquilae, δ Aquilae, ν Aquilae, 42 Aquilae, HD 184701, κ Aquilae and 56 Aquilae.[9] Consequently, ι Aquilae itself is known as 右旗五 (Yòu Qí wu, English: the Fifth Star of Right Flag.)[10]
Although Iota Aquilae is listed in star catalogues as a giant star, calculations of its dimension show that in reality it is a main-sequence star.[11] It has nearly five times the mass of the Sun and five to six times the Sun's radius.[5] It is emitting 851[5] times the luminosity of the Sun from its outer atmosphere at an effective temperature of 14,552 K,[6] giving it the blue-white hue of a B-type star. The projected rotational velocity of this star is 55 km/s.[7] Even though it is only around 100 million years old, it has already spent 91% of its allotted lifetime on the main sequence.[5]
References
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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) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
