Mu Aquilae

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Mu Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings
Cercle rouge 100%.svg
Location of μ Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension  19h 34m 05.3529s[1]
Declination +07° 22′ 44.189″[1]
Apparent magnitude (V) 4.45[2]
Spectral type K3 III[3]
U−B color index +1.24[2]
B−V color index +1.176[4]
R−I color index 0.61
Radial velocity (Rv)-24.73 ± 0.13[5] km/s
Proper motion (μ) RA: +213.73[1] mas/yr
Dec.: -156.55[1] mas/yr
Parallax (π)30.31 ± 0.24[1] mas
Distance107.6 ± 0.9 ly
(33.0 ± 0.3 pc)
Absolute magnitude (MV)1.80[5]
Mass0.92[5] M
Radius8[4] R
Luminosity24.5[4] L
Surface gravity (log g)2.6[4] cgs
Temperature4,467[4] K
Metallicity [Fe/H]–0.13[4] dex
Rotational velocity (v sin i)0.0[4] km/s
Other designations
38 Aql, BD+07 4132, FK5 1511, GJ 9661, HD 184406, HIP 96229, HR 7429, LTT 15709, SAO 124799.[6]
Database references

Mu Aquilae (μ Aql, μ Aquilae) is the Bayer designation for a star in the equatorial constellation of Aquila. With an apparent visual magnitude of 4.45,[2] it is visible to the naked eye. The measured annual parallax shift of 30.31 mas,[1] which is equivalent to a distance of 107.6 light-years (33.0 parsecs) from Earth.

The stellar classification of Mu Aquilae is K3 III,[3] indicating that this is an evolved giant star, it belongs to a sub-category called the red clump, indicating that it is generating energy through the fusion of helium at its core.[7] Compared to the Sun, it has 92%[5] of the mass but has expanded to eight times the size;[4] this inflated outer envelope has an effective temperature of 4,467 K[4] and is radiating 24.5[4] times the Sun's luminosity. At this heat, Mu Aquilae glows with the orange hue of a K-type star.[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:0708.1752, 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 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
  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 d Hekker, S.; et al. (August 2006), "Precise radial velocities of giant stars. I. Stable stars", Astronomy and Astrophysics, 454 (3): 943–949, arXiv:astro-ph/0604502, Bibcode:2006A&A...454..943H, doi:10.1051/0004-6361:20064946
  6. ^ "* mu. Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-18.
  7. ^ Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16.

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