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.
In 1965, Pavel Mayer reported that the star, then called HD 35921, is a variable star. By 1968, he had determined that it is an eclipsing binary.[10] It was given its variable star designation, LY Aurigae, in 1970.[11] 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.[12] 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]
Notes
^Using LY Aurigae's distance modulus of 11.6, its distance from Earth can be calculated by the following equation:
^ abStickland, 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.
^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.
^ abMayer, P.; Papoušek, J. (1988). "New photometric data on LY Aurigae". Contributions of the Astronomical Institute of Brno. 26. Bibcode:1988CoBrn..26.....M.
