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Eta Lyrae

Eta Lyrae
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra
Right ascension 19h 13m 45.48832s[1]
Declination +39° 08′ 45.4801″[1]
Apparent magnitude (V) 4.43[2]
Characteristics
Spectral type B2.5IV[3]
B−V color index −0.150±0.002[2]
Astrometry
Radial velocity (Rv)−8.1±0.9[1] km/s
Proper motion (μ) RA: −0.60[1] mas/yr
Dec.: −1.26[1] mas/yr
Parallax (π)2.35 ± 0.13 mas[1]
Distance1,390 ± 80 ly
(430 ± 20 pc)
Absolute magnitude (MV)−3.71[2]
Orbit[4]
Period (P)56.4±0.5 d
Semi-major axis (a)≥ 1.841 Gm (0.01231 AU)
Eccentricity (e)0.53±0.12
Periastron epoch (T)2,441,868.4±3.4 JD
Argument of periastron (ω)
(secondary)		337±28°
Semi-amplitude (K1)
(primary)		2.8±0.5 km/s
Details
Mass9.97±0.98 M☉[5]
10.1±1.0[6] M☉
Radius4.3[7] R☉
Luminosity6,605[2] L☉
Luminosity (bolometric)19,095[5] L☉
Surface gravity (log g)3.38[8] cgs
Temperature17,360 K[8]
19,525[5] K
Metallicity [Fe/H]−0.01[8] dex
Rotational velocity (v sin i)10[9] km/s
Age22.5±2.6[6] Myr
Other designations
Eta Lyr or η Lyr, 20 Lyr, BD+38°3490, HD 180163, HIP 94481, HR 7298, SAO 68010, WDS 19138+3909[10]
Database references
SIMBADdata

Eta Lyrae, a name Latinized from η Lyrae, is a likely binary star[11] system in the northern constellation of Lyra. It has the traditional name Aladfar /əˈlædfɑːr/ and is faintly visible to the naked eye with an apparent visual magnitude of 4.43.[2] The system is located at a distance of approximately 1,390 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s.[1]

  1. ^ a b c d e f g Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Lesh1968 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Abt_Levy_1978 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Hohle_et_al_2010 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Tetzlaff_et_al_2011 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Pasinetti_Fracassini_et_al_2001 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Cenarro_et_al_2007 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Prugniel_et_al_2011 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Eggleton_Tokovinin_2008 was invoked but never defined (see the help page).
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