12 Aquilae

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This article is about i Aquilae. It is not to be confused with ι Aquilae or l Aquilae.
12 Aquilae
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[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
i Aquilae, BD–05 4840, HD 176678, HIP 93429, HR 7193, SAO 142931.[6]
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.

Sometimes, this star is called by the name Bered, derived the Hebrew word בָּרָד barad, meaning "storm".[citation needed] 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[edit]

  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ 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. 
  4. ^ 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. 
  5. ^ 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:0712.1370Freely accessible, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788. 
  6. ^ "i Aql -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-22. 
  7. ^ (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.
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16. 

External links[edit]