Rho Aquilae

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ρ Aquilae
Delphinus constellation map.svg
Red circle.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
Distance150 ± 2 ly
(46.0 ± 0.5 pc)
Absolute magnitude (MV)+1.63[5]
Luminosity19.5[5] L
Surface gravity (log g)4.07±0.07[6] cgs
Temperature8,804±95[6] K
Metallicity [Fe/H]−0.48±0.10[6] dex
Rotational velocity (v sin i)180[7] km/s
Age50[8] to 120[9] Myr
Other designations
Tso Ke, ρ Aql, 67 Aquilae, BD+14° 4227, FK5 1526, HD 192425, HIP 99742, HR 7724, SAO 105878[10]
Database references

Rho Aquilae, ρ Aquilae, is the Bayer designation for a star in the northern constellation of Delphinus. It has an apparent visual magnitude of 4.94[2] and is bright enough to be seen with the naked eye in good conditions.

Distance, proper motion and constellation[edit]

Parallax shift (measured at any interval of half of a year) is 21.75 milliarcseconds,[1] which corresponds to a distance of the star of around 150 light-years (46 parsecs) from Earth. Relatively high proper motion resulted in the star crossing the border from Aquila into Delphinus in 1992.[11][12] Rho Aquilae is therefore a rare occurrence of a mismatch between current constellation and Bayer designation constellation; the star is in the low-northern constellation of Delphinus therefore at least seasonally visible to all but the high southern latitudes.

Chinese constellations and components[edit]

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), within the Ox, refers to an asterism consisting of this star, α, β, γ, δ, ζ, 11, 13, and 14 Sagittae (stars of Sagittarius) to the south.[13] Consequently, ρ Aquilae itself is known as 左旗九 (Zuǒ Qí jiǔ, English: the Ninth Star of Left Flag.)[14]

Physical characteristics[edit]

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.[8][9]


  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:0708.1752, 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 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. ^ a b c Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters", Astronomy and Astrophysics, 525: A71, arXiv:1009.1491, Bibcode:2011A&A...525A..71W, doi:10.1051/0004-6361/201015014.
  7. ^ 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/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  8. ^ 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/0010102, Bibcode:2001ApJ...546..352S, doi:10.1086/318269.
  9. ^ 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.
  10. ^ "* rho Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-20.
  11. ^ 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..221L
  12. ^ Patrick Moore (29 June 2013). The Observer’s Year: 366 Nights of the Universe. Springer Science & Business Media. pp. 132–. ISBN 978-1-4471-3613-2.
  13. ^ ‹See Tfd›(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.
  14. ^ ‹See Tfd›(in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日

External links[edit]