EQ Tauri is atriple star system in theequatorialconstellation ofTaurus that includes acontacteclipsing binary. The system is too faint to be viewed with the naked eye, having a baselineapparent visual magnitude of 10.5.[3] During the primary eclipse, the brightness of the system drops to magnitude 11.03, then to 10.97 during the secondary minimum.[3] The secondary eclipse is total.[7] Based onparallax measurements, it is located at a distance of approximately 730 light years from theSun.[2]
This is a shallow contact binary system,[7] belonging to sub-type A of the W Ursae Majoris class.[3] It has an orbital period of 8.1924 hours[6] and asemimajor axis of 2.48 times the radius of the Sun. The orbit shows a cyclical change with a period of 22.7 years and anamplitude of 0.0058 days. Atransit-like event was observed in 2010.[7] The more massive component is a solar-type star with a deepconvection zone that appearsmagnetically active with a significant coverage ofstar spots.[4]
^abYuan, Jinzhao; Qian, Shengbang (October 2007), "Variation of the period and light curves of the solar-type contact binary EQ Tauri",Monthly Notices of the Royal Astronomical Society,381 (2):602–610,Bibcode:2007MNRAS.381..602Y,doi:10.1111/j.1365-2966.2007.11926.x.
^Shapley, Harlow; Hughes, Emily M. (1940), "Variable stars in high galactic latitudes",Annals of the Astronomical Observatory of Harvard College,90 (4):163–175,Bibcode:1940AnHar..90..163S.
^Artiukhina, N. M. (1961), "Proper Motions of three W UMa Type Stars in the Pleiades Region",Peremennye Zvezdy (in Russian),13: 366,Bibcode:1961PZ.....13..366A.
^Whitney, B. S. (February 1972), "The Period of EQ Tauri",Information Bulletin on Variable Stars,633 (1): 1,Bibcode:1972IBVS..633....1W.
^Benbow, W. R.; Mutel, R. L. (May 1995), "Eclipse Observations of EQ Tau",Information Bulletin on Variable Stars,4187 (1): 1,Bibcode:1995IBVS.4187....1B.
^Pribulla, T.; Vanko, M. (April 2002), "Photoelectric photometry of eclipsing contact binaries: U Peg, YY CrB, OU Ser and EQ Tau",Contributions of the Astronomical Observatory Skalnate Pleso,32 (1):79–98,Bibcode:2002CoSka..32...79P.
Tvardovskyi, D. E. (January 2020), "Third components with elliptical orbits in the eclipsing binaries: EQ Tau, IR Cas, IV Cas, RY Aqr & RZ Com",Annales Astronomiae Novae,1:231–238,arXiv:1912.12639,Bibcode:2020AANv....1..231T.
Alton, K. B. (December 2009), "A Multi-year Multi-passband CCD Photometric Study of the W UMa Binary EQ Tauri",The Journal of the American Association of Variable Star Observers,37 (2): 148,Bibcode:2009JAVSO..37..148A.
Hrivnak, Bruce J.; Lu, Wenxian; Eaton, Jeffery; Kenning, Daniel (August 2006), "Light-Curve Study and Physical Properties of the Contact Binary EQ Tauri",The Astronomical Journal,132 (2):960–966,Bibcode:2006AJ....132..960H,doi:10.1086/505691,S2CID120523899.
Alton, Kevin B. (June 2006), "A Backyard CCD Photometric Study of the Neglected W UMa Binary EQ Tauri",Open European Journal on Variable Stars,39: 1,Bibcode:2006OEJV...39....1A.
Vaňko, M.; et al. (2004), "New Parameters of the Contact Binary Systems YY CRB and EQ Tau",Baltic Astronomy,13:151–155,Bibcode:2004BaltA..13..151V.
Qian, Shengbang; Ma, Yuan (June 2001), "Period Studies of Some Neglected Close Binaries: EP Andromedae, V724 Aquilae, SS Comae, AM Eridani, FZ Orionis, BY Pegasi, EQ Tauri, and NO Vulpeculae",The Publications of the Astronomical Society of the Pacific,113 (784):754–763,Bibcode:2001PASP..113..754Q,doi:10.1086/320808,S2CID121169370.
Buckner, M.; et al. (February 1998), "Eclipse Timing Observations of Three Close Binaries",Information Bulletin on Variable Stars,4559 (1): 1,Bibcode:1998IBVS.4559....1B.
