LY Aurigae

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

LY Aurigae is the bright star in the southeast corner of this picture of Messier 38
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])
Characteristics
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]
Astrometry
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
Distanceapprox. 1,000 ly
(approx. 300 pc)
Absolute magnitude (MV)5.62 + 5.11 + 4.43[4]
Orbit[4]
PrimaryAa
CompanionAb
Period (P)4.0025 days
Semi-major axis (a)36.1 R☉
Eccentricity (e)0.0
Inclination (i)87.7°
Semi-amplitude (K1)
(primary)
161.9 km/s
Semi-amplitude (K2)
(secondary)
294.3 km/s
Orbit[4]
PrimaryBa
CompanionBb
Period (P)20.4642 days
Eccentricity (e)0.246
Semi-amplitude (K1)
(primary)
33.0 km/s
Details[4]
Aa
Mass25.5 M
Radius16.1 R
Luminosity214,000 L
Surface gravity (log g)3.425 cgs
Temperature31,000 K
Rotational velocity (v sin i)194 km/s
Ab
Mass14.0 M
Radius12.6 R
Luminosity135,000 L
Surface gravity (log g)3.378 cgs
Temperature31,150 K
Rotational velocity (v sin i)152 km/s
B
Luminosity47,000 L
Surface gravity (log g)4.00 cgs
Temperature26,000 K
Rotational velocity (v sin i)30 km/s
Age5 Myr
Other designations
LY Aurigae, BD+35°1137, HD 35921, SAO 58105, HIP 25733, WDS J05297+3523, AAVSO 0523+35
Database references
SIMBADdata

System

LY Aurigae is a 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]

References

  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
  2. 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. 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. 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): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  7. Paunzen, E. (2015). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy & Astrophysics. 580: A23. arXiv:1506.04568. Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. S2CID 73623700.
  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: 180–189. 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.

See also

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