12 Aquilae

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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 Aql, BD–05 4840, HD 176678, HIP 93429, HR 7193, SAO 142931.[6]

12 Aquilae (12 Aql) is the Flamsteed designation for a star in the equatorial constellation of Aquila. It has the Bayer designation i Aquilae (i Aql). Sometimes, this star is called by the name Bered, derived the Hebrew word בָּרָד barad, meaning "storm". 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:0708.1752, 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:0712.1370, 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]