 A visual band light curve for EQ Tauri, plotted from ASAS-SN data | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 03 48 13.436 |
| Declination | +22° 18′ 50.92″ |
| Apparent magnitude (V) | 10.5 (-11.03) |
| Characteristics | |
| Spectral type | G2 |
| Variable type | W UMa |
| Astrometry | |
| Radial velocity (Rv) | 71.95±1.22 km/s |
| Proper motion (μ) | RA: +69.758 mas/yr Dec.: −30.628 mas/yr |
| Parallax (π) | 4.4694 ± 0.0171 mas |
| Distance | 730 ± 3 ly (223.7 ± 0.9 pc) |
| Orbit | |
| Period (P) | 0.341348 d |
| Semi-major axis (a) | 2.48±0.03 R☉ |
| Eccentricity (e) | 0.00 |
| Periastron epoch (T) | 2,451,183.9 HJD |
| Semi-amplitude (K1) (primary) | 112.41±1.43 km/s |
| Semi-amplitude (K2) (secondary) | 254.38±2.42 km/s |
| Details | |
| Primary | |
| Mass | 1.22±0.04 M☉ |
| Radius | 1.14±0.01 R☉ |
| Luminosity | 1.32±0.03 L☉ |
| Temperature | 5,800±100 K |
| Secondary | |
| Mass | 0.54±0.02 M☉ |
| Radius | 0.79±0.01 R☉ |
| Luminosity | 0.63±0.02 L☉ |
| Other designations | |
| EQ Tau, TIC 440686937, GSC 01260-00909, 2MASS J03481342+2218509, HV 6189 | |
| Database references | |
| SIMBAD | data |
EQ Tauri is a triple star system in the equatorial constellation of Taurus that includes a contact eclipsing binary. The system is too faint to be viewed with the naked eye, having a baseline apparent visual magnitude of 10.5. During the primary eclipse, the brightness of the system drops to magnitude 11.03, then to 10.97 during the secondary minimum. The secondary eclipse is total. Based on parallax measurements, it is located at a distance of approximately 730 light years from the Sun.
The star HV 6189 was identified as a short-period variable by H. Shapley and E. M. Hughes in 1940, then was more closely studied by Soviet astronomer V. P. Tsesevich in 1954. It was determined to be a W UMa-type variable and was noted for being located in the region of the Pleiades open cluster. An analysis of data from Tsesevich and subsequent observations by B. S. Whitney in 1972 suggested that the period is variable. His observations from Konkoly Observatory showed a period of 8.19 h. W. R. Benbow and R. L. Mutel built a light curve of the eclipsing variable in 1995 that displayed evidence of an active region on the stellar surface. Orbital period changes continued to be observed, and in 2002 T. Pribulla and M. Vanko suggested it is caused by a third body in the system. They modeled it as a low mass red dwarf with an orbital period of 50.2 years.
This is a shallow contact binary system, belonging to sub-type A of the W Ursae Majoris class. It has an orbital period of 8.1924 hours 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. 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.
References
- "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
- ^ Yuan, 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.
- Bilir, S.; et al. (2005), "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation", Monthly Notices of the Royal Astronomical Society, 357 (2): 497–517, arXiv:astro-ph/0411291, Bibcode:2005MNRAS.357..497B, doi:10.1111/j.1365-2966.2005.08609.x, S2CID 16274339.
- ^ Rucinski, Slavek M.; et al. (October 2001), "Radial Velocity Studies of Close Binary Stars. V.", The Astronomical Journal, 122 (4): 1974–1980, arXiv:astro-ph/0106160, Bibcode:2001AJ....122.1974R, doi:10.1086/323106.
- ^ Li, K.; et al. (May 2014), "The Triple Binary Star EQ Tau with an Active Component", The Astronomical Journal, 147 (5): 8, Bibcode:2014AJ....147...98L, doi:10.1088/0004-6256/147/5/98, S2CID 123566937, 98.
- "EQ Tau", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2022-03-13.
- 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.
Further reading
- 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.
- Hasanzadeh, A.; et al. (January 2015), "New light curve analysis and period changes of the overcontact binary EQ Tauri", New Astronomy, 34: 262–265, Bibcode:2015NewA...34..262H, doi:10.1016/j.newast.2014.07.013.
- Elkhateeb, M. M.; Nouh, M. I. (2014), "A holistic study of the eclipsing binary EQ Tau" (PDF), Journal of Physics and Astronomy Research, 1 (3): 15, arXiv:1406.1661, retrieved 2022-03-13.
- 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, S2CID 120523899.
- 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.
- Yang, Yulan; Liu, Qingyao (December 2002), "A Photometric Study of the Contact Binary EQ Tauri", The Astronomical Journal, 124 (6): 3358–3363, Bibcode:2002AJ....124.3358Y, doi:10.1086/344763, S2CID 123447240.
- 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, S2CID 121169370.
- 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.
