Mu Lyrae

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Mu Lyrae
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra
Right ascension 118h 24m 13.78580s[1]
Declination +39° 30′ 26.0562″[1]
Apparent magnitude (V) 5.12[2]
Spectral type A0 IV[3]
U−B color index +0.07[4]
B−V color index +0.04[4]
Radial velocity (Rv) -24.0 ± 2[1] km/s
Proper motion (μ) RA: -21.14 ± 0.15[1] mas/yr
Dec.: -4.91 ± 0.17[1] mas/yr
Parallax (π) 7.43 ± 0.16[1] mas
Distance 439 ± 9 ly
(135 ± 3 pc)
Mass 3.04±0.04[5] M
Luminosity 125[6] L
Temperature 8190[6] K
Rotational velocity (v sin i) 165[5] km/s
Other designations
2 Lyr, HD 169702, HIP 90191, HR 6903, SAO 66943, BD+39° 3410[2]
Database references

Mu Lyrae (μ Lyr, μ Lyrae) is a star in the constellation Lyra. It has the traditional name Alathfar, from the Arabic الأظفر al-’uz̧fur "the talons (of the swooping eagle)", a name it shares with Eta Lyrae (though the latter is typically spelled Aladfar in English).[citation needed]

Mu Lyrae has apparent magnitude 5.12 and belongs to the spectral class A0IV.[2] Located around 439 light-years distant, it shines with a luminosity approximately 125 times that of the Sun and has a surface temperature of 8190 K.[6]


  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, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c "mu Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. 
  3. ^ Van Belle, Gerard T.; von Braun, Kaspar (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085. doi:10.1088/0004-637X/694/2/1085. 
  4. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Bibcode:1986EgUBV........0M. 
  5. ^ a b Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, Bibcode:2012A&A...537A.120Z, arXiv:1201.2052Freely accessible, doi:10.1051/0004-6361/201117691. 
  6. ^ a b c McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. Bibcode:2012MNRAS.427..343M. arXiv:1208.2037Freely accessible. doi:10.1111/j.1365-2966.2012.21873.x.