EQ Tauri is a triple star system in the equatorialconstellationofTaurus that includes a contacteclipsing binary. The system is too faint to be viewed with the naked eye, having a baseline apparent 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 on parallax measurements, it is located at a distance of approximately 730 light years from the Sun.[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 a semimajor axis of 2.48 times the radius of the Sun. The orbit shows a cyclical change with a period of 22.7 years and an amplitude of 0.0058 days. A transit-like event was observed in 2010.[7] The more massive component is a solar-type star with a deep convection zone that appears magnetically active with a significant coverage of star 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.
