Zeta1 Lyrae

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Zeta1 Lyrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lyra
Right ascension 18h 44m 46.35735s[1]
Declination +37° 36′ 18.4171″[1]
Apparent magnitude (V) 4.37[2]
Spectral type kA5hF0mF2[3]
U−B color index +0.17[2]
B−V color index +0.18[2]
Proper motion (μ) RA: +29.04[1] mas/yr
Dec.: +27.03[1] mas/yr
Parallax (π)20.89 ± 0.17[1] mas
Distance156 ± 1 ly
(47.9 ± 0.4 pc)
Absolute magnitude (MV)+0.94[4]
Period (P)4.3 d
Eccentricity (e)0.01
Periastron epoch (T)2440000.723 JD
Argument of periastron (ω)
Semi-amplitude (K1)
51.6 km/s
Mass2.36[6] M
Radius2.5[7] R
Luminosity31[8] L
Surface gravity (log g)3.7±0.1[9] cgs
Temperature7914±112[9] K
Metallicity [Fe/H]0.38±0.06[9] dex
Rotational velocity (v sin i)47[10] km/s
Age500[6] Myr
Other designations
ζ1 Lyr, 6 Lyr, BD+37° 3222, HD 173648, HIP 91971, HR 7056, SAO 67321.[11]
Database references

Zeta1 Lyrae, Latinized from ζ1 Lyrae, is a binary star in the northern constellation of Lyra. Based upon an annual parallax shift of 20.89 mas as seen from Earth,[1] the pair are located about 156 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.37.[2]

Observational history[edit]

ζ1 Lyrae was discovered to be a spectroscopic binary by William Wallace Campbell and Heber Doust Curtis in 1905 from photographic plates taken at the Lick Observatory between 1902 and 1904.[12] The first orbit was calculated by Frank Craig Jordan of Allegheny Observatory in 1910 with results in good agreement with the most recent orbit.[13]

Binary system[edit]

This is a single-lined spectroscopic binary system with an orbital period of 4.3 days and a nearly circular orbit with an eccentricity of 0.01.[5] The primary, component A, is an Am star with a stellar classification of kA5hF0mF2. This complex notation indicates that the spectral type determined solely from the calcium K line would be A5, the spectral type determined from other metallic lines would be F2, and the type determined from hydrogen lines would be F0.[3]


ζ1 Lyrae appears to be slightly variable, with a frequency of 0.65256 cycles per day and an amplitude of 0.0032 in magnitude.[14] The star has an estimated 2.36[6] times the mass of the Sun and around 2.5[7] times the Sun's radius. The position of this system is associated with an X-ray source with a luminosity of 571.6×1020 W.[15]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182. 
  4. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  5. ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, arXiv:astro-ph/0406573Freely accessible, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213. 
  6. ^ a b c De Rosa, R. J.; et al. (2013), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216, arXiv:1311.7141Freely accessible, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932. 
  7. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367 (2): 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  8. ^ McDonald, I.; et al. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv:1208.2037Freely accessible. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. 
  9. ^ a b c Prugniel, Ph.; et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952Freely accessible, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769. 
  10. ^ Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393 (3): 897–911, arXiv:astro-ph/0205255Freely accessible, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  11. ^ "* zet01 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-17. 
  12. ^ Campbell, W. W.; Curtis, H. D. (1905). "A list of nine stars whose radial velocities vary". The Astrophysical Journal. 21: 189. Bibcode:1905ApJ....21..185C. doi:10.1086/141200. 
  13. ^ Jordan, Frank Craig (1910). "The orbit of ζ1 Lyrae". Publications of the Allegheny Observatory of the University of Pittsburgh. 1 (17): 115–118. Bibcode:1910PAllO...1..115J. 
  14. ^ Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331: 45, arXiv:astro-ph/0112194Freely accessible, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x. 
  15. ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.