Rho Aquilae

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Rho Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings
Cercle rouge 100%.svg

Location of ρ Aquilae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Delphinus
Right ascension 20h 14m 16.61886s[1]
Declination +15° 11′ 51.3923″[1]
Apparent magnitude (V) 4.94[2]
Spectral type A2 V[3]
U−B color index +0.01[4]
B−V color index +0.09[4]
Radial velocity (Rv) –23.0[2] km/s
Proper motion (μ) RA: +55.03[1] mas/yr
Dec.: +58.14[1] mas/yr
Parallax (π) 21.75 ± 0.26[1] mas
Distance 150 ± 2 ly
(46.0 ± 0.5 pc)
Surface gravity (log g) 4.07 ± 0.07[5] cgs
Temperature 8,804 ± 95[5] K
Metallicity [Fe/H] –0.48 ± 0.10[5] dex
Rotational velocity (v sin i) 180[6] km/s
Age 50[7] to 120[8] Myr
Other designations
Tso Ke, 67 Aquilae, BD+14 4227, FK5 1526, HD 192425, HIP 99742, HR 7724, SAO 105878.[9]
Database references

Rho Aquilae (ρ Aql, ρ Aquilae) is the Bayer designation for a star in the northern constellation of Delphinus – it moved across the border from Aquila into Delphinus in 1992.[10] It has an apparent visual magnitude of 4.94[2] and is bright enough to be seen with the naked eye in good conditions. The annual parallax shift of this star is 21.75 milliarcseconds,[1] which corresponds to a physical distance of around 150 light-years (46 parsecs) from Earth.

This star has the traditional name Tso Ke, from the Cantonese 左旗 jo keih meaning "the left flag". In Chinese, 左旗 (Zuǒ Qí in Mandarin), meaning Left Flag, refers to an asterism consisting of ρ Aquilae, α Sagittae, β Sagittae, δ Sagittae, ζ Sagittae, γ Sagittae, 13 Sagittae, 11 Sagittae and 14 Sagittae.[11] Consequently, ρ Aquilae itself is known as 左旗九 (Zuǒ Qí jiǔ, English: the Ninth Star of Left Flag.)[12]

Rho Aquilae is an A-type main sequence star with a stellar classification of A2 V.[3] This star is about 50 to 120 million years old and it displays an excess emission of infrared radiation that may be explained by a circumstellar disk of dust.[7][8]


  1. ^ a b c d e f 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 Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W. 
  3. ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819. 
  4. ^ a b 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. 
  5. ^ a b c Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters", Astronomy and Astrophysics, 525: A71, arXiv:1009.1491Freely accessible, Bibcode:2011A&A...525A..71W, doi:10.1051/0004-6361/201015014. 
  6. ^ Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785Freely accessible, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224. 
  7. ^ a b Song, Inseok; et al. (February 2001), "Ages of A-Type Vega-like Stars from uvbyβ Photometry", The Astrophysical Journal, 546 (1): 352–357, arXiv:astro-ph/0010102Freely accessible, Bibcode:2001ApJ...546..352S, doi:10.1086/318269. 
  8. ^ a b Morales, Farisa Y.; et al. (April 2011), "Common Warm Dust Temperatures Around Main-sequence Stars", The Astrophysical Journal Letters, 730 (2): L29, Bibcode:2011ApJ...730L..29M, doi:10.1088/2041-8205/730/2/L29. 
  9. ^ "rho Aql -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-20. 
  10. ^ Hirshfeld, A.; et al. (August 1992), "Book-Review - Sky Catalogue 2000.0 - V.1 - Stars to Magnitude 8.0 ED.2", Journal of the Royal Astronomical Society of Canada, 86 (4): 221, Bibcode:1992JRASC..86..221H 
  11. ^ (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.
  12. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日

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