Mu Lyrae

Mu Lyrae
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra
Right ascension 18h 24m 13.78599s[1]
Declination +39° 30′ 26.0473″[1]
Apparent magnitude (V) 5.11[2]
Characteristics
Evolutionary stage subgiant[3]
Spectral type A0 IV[4]
U−B color index +0.07[5]
B−V color index +0.047±0.004[2]
Astrometry
Radial velocity (Rv)−24.0±4.2[2] km/s
Proper motion (μ) RA: −21.825±0.260[1] mas/yr
Dec.: −4.460±0.288[1] mas/yr
Parallax (π)7.9161 ± 0.1438 mas[1]
Distance412 ± 7 ly
(126 ± 2 pc)
Absolute magnitude (MV)–0.53[2]
Details
Mass3.04±0.04[3] M☉
Radius4.5[6] R☉
Luminosity200+23
−10[3] L☉
Temperature9,016+167
−165[3] K
Rotational velocity (v sin i)165[3] km/s
Other designations
μ Lyr, 2 Lyrae, BD+39°3410, HD 169702, HIP 90191, HR 6903, SAO 66943[7]
Database references
SIMBADdata

μ Lyrae, Latinized as Mu Lyrae, is a solitary[8] star in the northern constellation Lyra. It has the traditional name Alathfar /əˈlæθfɑːr/, from the Arabic الأظفار al-ʼaẓfār "the talons (of the swooping eagle)", a name it shares with Eta Lyrae[9] (though the latter is spelled "Aladfar" by the IAU).[10] This white-hued object is visible to the naked eye as faint point of light with an apparent visual magnitude of 5.11.[2] It is located approximately 412 light years distant from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −24 km/s.[2]

This object has evolved off the main sequence,[3] becoming a subgiant with a stellar classification of A0 IV.[4] It has a fairly high rate of spin, showing a projected rotational velocity of 165 km/s.[3] This is giving the star an equatorial bulge that is an estimated 17% larger than the polar radius.[11] The star has three[3] times the mass of the Sun and about 4.5[6] times the Sun's radius. It is radiating 200[3] times the Sun's luminosity from its photosphere at an effective temperature of 9,016 K.[3]

  1. ^ a b c d e f Cite error: The named reference dr2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i j Cite error: The named reference Zorec2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference vanBelle2009 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference UBV was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Fracassini2001 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference allen was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference vanBelle2012 was invoked but never defined (see the help page).