Astronomy:12 Aquilae
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| 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 does not have a Bayer designation 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
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 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.
- ↑ 3.0 3.1 Roman, Nancy G. (July 1952), "The Spectra of the Bright Stars of Types F5-K5", Astrophysical Journal 116: 122, doi:10.1086/145598, Bibcode: 1952ApJ...116..122R.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 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, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M.
- ↑ 5.0 5.1 5.2 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, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S.
- ↑ "i Aql". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=i+Aql.
- ↑ (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, https://web.archive.org/web/20120222183238/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16.
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