  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 01m 40.82707s [1] |
| Declination | –05° 44′ 20.8134″ [1] |
| Apparent magnitude (V) | 4.02 [2] |
| Characteristics | |
| Spectral type | K1 III [3] |
| U−B color index | +1.04 [2] |
| B−V color index | +1.104 [4] |
| R−I color index | 0.54 |
| Astrometry | |
| Radial velocity (Rv) | –43.92 ± 0.18 [4] km/s |
| Proper motion (μ) |
RA: –24.41
[1]
mas/
yr Dec.: –39.66 [1] mas/ yr |
| Parallax (π) | 22.66 ± 0.23 mas [1] |
| Distance | 144 ± 1
ly (44.1 ± 0.4 pc) |
| Absolute magnitude (MV) | 0.726 [5] |
| Details | |
| Radius | 12 [4] R☉ |
| Luminosity | 60 [4] L☉ |
| Surface gravity (log g) | 2.6 [4] cgs |
| Temperature | 4,603 [4] K |
| Metallicity [Fe/H] | –0.19 [5] dex |
| Rotational velocity (v sin i) | 3.6 [4] km/s |
| Age | 4.64 ± 2.35 [5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
12 Aquilae (abbreviated 12 Aql) is a star in the equatorial constellation of Aquila. 12 Aquilae has the Bayer designation of i Aquilae and is most easily recognized in the sky being next to the brighter star λ (lambda) Aquilae.
In Chinese, 天弁 (Tiān Biàn), meaning Market Officer, refers to an asterism consisting of 12 Aquilae, α Scuti, δ Scuti, ε Scuti, β Scuti, η Scuti, λ Aquilae, 15 Aquilae and 14 Aquilae. [7] Consequently, 12 Aquilae itself is known as 天弁六 (Tiān Biàn liù, English: the Sixth Star of Market Officer.)
This star has an apparent visual magnitude of 4.02, [2] which is bright enough to be seen with the naked eye, although, according to the Bortle Dark-Sky Scale, it is a challenge to view from the inner city. Based upon an annual parallax shift of 22.66 mas, the distance to this star is 144 light-years (44 parsecs) with a margin of error of one light-year. This is an evolved giant star of stellar class K1 III. [3] It has 12 [4] times the radius of the Sun and shines with 60 [4] times the Sun's luminosity. This energy is being radiated from its outer atmosphere at an effective temperature of 4,603 K, [4] giving it the cool orange hue of a K-type star. [8]
References
- ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752, Bibcode: 2007A&A...474..653V, doi: 10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ^ a b Roman, Nancy G. (July 1952), "The Spectra of the Bright Stars of Types F5-K5", Astrophysical Journal, 116: 122, Bibcode: 1952ApJ...116..122R, doi: 10.1086/145598.
- ^ a b c d e f g h i j Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode: 2008AJ....135..209M, doi: 10.1088/0004-6256/135/1/209, S2CID 121883397.
- ^ a b c Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv: 0712.1370, Bibcode: 2008A&A...480...91S, doi: 10.1051/0004-6361:20078788, S2CID 16602121.
- ^ "i Aql", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-07-22.
- ^ (in 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.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16.
