LY Aurigae

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LY Aurigae
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 29m 42.650s[1]
Declination +35° 22′ 30.09″[1]
Apparent magnitude (V) 6.85[2] (6.66 - 7.35[3])
Spectral type O9II + O9III + B0.5III[4]
U−B color index −0.78[5]
B−V color index +0.20[5]
Variable type β Lyr[2]
Radial velocity (Rv) 5.40[6] km/s
Proper motion (μ) RA: −0.20 ± 3.19[1] mas/yr
Dec.: −1.17 ± 2.07[1] mas/yr
Parallax (π) 3.28 ± 2.40[1] mas
Distance approx. 1,000 ly
(approx. 300 pc)
Absolute magnitude (MV) −5.62 + −5.11 + −4.43[4]
Primary Aa
Companion Ab
Period (P) 4.0025 days
Semi-major axis (a) 36.1 AU
Eccentricity (e) 0.0
Inclination (i) 87.7°
Semi-amplitude (K1)
161.9 km/s
Semi-amplitude (K2)
294.3 km/s
Primary Ba
Companion Bb
Period (P) 20.4642 days
Eccentricity (e) 0.246
Semi-amplitude (K1)
33.0 km/s
Mass 25.5 M
Radius 16.1 R
Luminosity 214,000 L
Surface gravity (log g) 3.425 cgs
Temperature 31,000 K
Rotational velocity (v sin i) 194 km/s
Mass 14.0 M
Radius 12.6 R
Luminosity 135,000 L
Surface gravity (log g) 3.378 cgs
Temperature 31,150 K
Rotational velocity (v sin i) 152 km/s
Luminosity 47,000 L
Surface gravity (log g) 4.00 cgs
Temperature 26,000 K
Rotational velocity (v sin i) 30 km/s
Age Myr
Other designations
LY Aurigae, BD+35°1137, HD 35921, SAO 58105, HIP 25733, WDS J05297+3523, AAVSO 0523+35
Database references

LY Aurigae is a multiple star system in the constellation Auriga. It is an eclipsing binary variable star, dropping in brightness by 0.7 magnitudes every 4 days. The system is around a thousand light years away in the Auriga OB1 stellar association.


LY Aurigae is c close visual binary. The two stars are magnitude 6.85[7] and magnitude 8.35[8] 0.6 arc-seconds apart. Each star is also a spectroscopic binary.

LY Aur A is a double-lined spectroscopic binary with an O9 bright giant and an O9 giant star in contact and eclipsing each other as they orbit every 4 days. It is classified as a Beta Lyr eclipsing variable system. The primary eclipse is 0.69 magnitudes deep and the secondary eclipse is 0.60 magnitudes.[9] Because of the contact nature of the system and the deformed shapes of the stars, the magnitude varies constantly throughout the orbital cycle. The orbital period is slowly changing due to mass exchange between the stars. Each star is over a hundred thousand times the luminosity of the sun.[4]

LY Aur B is a single-lined spectroscopic binary with an orbital period of 20.5 days. It is probably an early B main sequence star and the companion is undetectable. The two stars combined are 47,000 times the luminosity of the sun.[4]


  1. ^ a b c d e 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.  Vizier catalog entry
  2. ^ a b Stickland, D. J.; et al. (1994). "Spectroscopic binary orbits from ultraviolet radial velocities. Paper 15: LY Aurigae (HD 35921)". The Observatory. 114: 107–113. Bibcode:1994Obs...114..107S. 
  3. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S. 
  4. ^ a b c d e f g Mayer, Pavel; Drechsel, Horst; Harmanec, Petr; Yang, Stephenson; Šlechta, Miroslav (2013). "The O-type eclipsing contact binary LY Aurigae - member of a quadruple system". Astronomy & Astrophysics. 559: A22. Bibcode:2013A&A...559A..22M. doi:10.1051/0004-6361/201322153. 
  5. ^ a b Mayer, P.; Papoušek, J. (1988). "New photometric data on LY Aurigae". Contributions of the Astronomical Institute of Brno. 26. Bibcode:1988CoBrn..26.....M. 
  6. ^ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727. arXiv:astro-ph/0406573Freely accessible. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. 
  7. ^ Paunzen, E. (2015). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy & Astrophysics. 580: A23. arXiv:1506.04568Freely accessible. Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. 
  8. ^ Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822. 
  9. ^ Malkov, O. Yu.; Oblak, E.; Snegireva, E. A.; Torra, J. (2006). "A catalogue of eclipsing variables". Astronomy and Astrophysics. 446 (2): 785. Bibcode:2006A&A...446..785M. doi:10.1051/0004-6361:20053137. 

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