EQ Tauri

Last updated
EQ Tauri
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Taurus
Right ascension 03h 48m 13.436s [1]
Declination +22° 18 50.92 [1]
Apparent magnitude  (V)10.5 (-11.03) [2]
Characteristics
Spectral type G2 [3]
Variable type W UMa [2]
Astrometry
Radial velocity (Rv)71.95±1.22 [4]  km/s
Proper motion (μ)RA: +69.758 [1]   mas/yr
Dec.: −30.628 [1]   mas/yr
Parallax (π)4.4694 ± 0.0171 [1]   mas
Distance 730 ± 3  ly
(223.7 ± 0.9  pc)
Orbit [5]
Period (P)0.341348 d
Semi-major axis (a)2.48±0.03  R [6]
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 [6]   M
Radius 1.14±0.01 [6]   R
Luminosity 1.32±0.03 [6]   L
Temperature 5,800±100 [6]   K
Secondary
Mass 0.54±0.02 [6]   M
Radius 0.79±0.01 [6]   R
Luminosity0.63±0.02 [6]   L
Other designations
EQ Tau, TIC  440686937, GSC  01260-00909, 2MASS J03481342+2218509, HV 6189 [7]
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. [2] During the primary eclipse, the brightness of the system drops to magnitude 11.03, then to 10.97 during the secondary minimum. [2] The secondary eclipse is total. [6] Based on parallax measurements, it is located at a distance of approximately 730  light years from the Sun. [1]

The star HV 6189 was identified as a short-period variable by H. Shapley and E. M. Hughes in 1940, [8] then was more closely studied by Soviet astronomer V. P. Tsesevich in 1954. [5] It was determined to be a W UMa-type variable and was noted for being located in the region of the Pleiades open cluster. [9] 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. [10] 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. [11] 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. [12]

This is a shallow contact binary system, [6] belonging to sub-type A of the W Ursae Majoris class. [2] It has an orbital period of 8.1924 hours [5] 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. [6] 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. [3]

Related Research Articles

W Ursae Majoris is the variable star designation for a binary star system in the northern constellation of Ursa Major. It has an apparent visual magnitude of about 7.9, which is too faint to be seen with the naked eye. However, it can be viewed with a small telescope. Parallax measurements place it at a distance of roughly 169 light years (52 parsecs) from Earth.

Xi Tauri is a hierarchical quadruple system in the constellation Taurus.

29 Aquarii Binary star in the constellation Aquarius


29 Aquarii is a binary star system located around 590 light years away from the Sun in the equatorial constellation of Aquarius. 29 Aquarii is the Flamsteed designation; the system also bears the variable star designation DX Aquarii. It is a challenge to view with the naked eye, appearing as a dim star with a combined apparent visual magnitude of 6.39. The system is moving further from the Earth with a heliocentric radial velocity of about +15 km/s.

Y Sextantis Variable star in the constellation Sextans

Y Sextantis, abbreviated as Y Sex, is a variable star system in the equatorial constellation of Sextans. The system is invisible to the naked eye with a mean apparent visual magnitude of 9.88. It is located roughly at 1,300 light years from the Sun based on parallax.

Eta Muscae is a multiple star system in the southern constellation of Musca. It is visible to the naked eye as a faint, blue-white hued point of light with an apparent visual magnitude of 4.79. The system is located around 406 light years away from the Sun. It is a member of the Lower Centaurs Crux subgroup of the Sco OB2 stellar association of co-moving stars.

V1191 Cygni Star in the constellation Cygnus

V1191 Cygni is the variable star designation for an overcontact binary star system in the constellation Cygnus. First found to be variable in 1965, it is a W Ursae Majoris variable with a maximum apparent magnitude 10.82. It drops by 0.33 magnitudes during primary eclipses with a period of 0.3134 days, while dropping by 0.29 magnitudes during secondary eclipses. The primary star, which is also the cooler star, appears to have a spectral type of F6V, while the secondary is slightly cooler with a spectral type of G5V. With a mass of 1.29 solar masses and a luminosity of 2.71 solar luminosities, it is slightly more massive and luminous than the sun, while the secondary is only around 1/10 as massive and less than half as luminous. With a separation of 2.20 solar radii, the mass transfer of about 2×10−7 solar masses per year from the secondary to the primary is one of the highest known for a system of its type.

HP Lyrae

HP Lyrae is a variable star in the constellation Lyra, with a visual magnitude varying between 10.2 and 10.8. It is likely to be an RV Tauri variable, an unstable post-AGB star losing mass before becoming a white dwarf.

RR Centauri Star in the constellation Centaurus

RR Centauri is a variable star of apparent magnitude maximum +7.29. It is located in the constellation of Centaurus, approximately 320 light years distant from the solar system.

HO Telescopii is an eclipsing binary star system located in the southern constellation of Telescopium. The maximum apparent visual magnitude of 8.22 is too faint to be visible to the naked eye. The system is located at a distance of approximately 910 light years based on parallax. The combined stellar classification of the system is A7III(m), matching an evolved A-type star that is possibly metallic-lined. The system is around 1.1 billion years old and consists of two stars of similar mass and size.

AB Andromedae Binary star in the Andromeda constellation

AB Andromedae is a binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 9.49 but shows a variation in brightness down to a magnitude of 10.46 in a periodic cycle of roughly 8 hours. The observed variability is typical of W Ursae Majoris variable stars, so the two stars in this system form a contact binary.

AE Phoenicis Star in the constellation Phoenix

AE Phoenicis is a variable star in the constellation of Phoenix. An eclipsing binary, its apparent magnitude has a maximum of 7.56, dimming to 8.25 during primary eclipse and 8.19 during secondary eclipse. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 168 light-years from Earth.

V752 Centauri Star in the constellation Centaurus

V752 Centauri is multiple star system and variable star in the constellation of Centaurus. An eclipsing binary, its apparent magnitude has a maximum of 9.10, dimming to 9.66 during primary eclipse and 9.61 during secondary eclipse. Its variability was discovered by Howard Bond in 1970. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 410 light-years from Earth.

RS Canum Venaticorum Binary star in the constellation Canes Venatici

RS Canum Venaticorum is a binary star system in the northern constellation of Canes Venatici. It serves as the prototype to the class of RS Canum Venaticorum variables. The peak apparent visual magnitude of this system is below the level needed to observe it with the naked eye. It is located at a distance of approximately 443 light years from the Sun based on parallax, but is drifting closer with a net radial velocity of −14 km/s. Olin J. Eggen (1991) included this system as a member of the IC 2391 supercluster, but it was later excluded.

HS Hydrae is a triple star system in the equatorial constellation of Hydra. The inner pair were an eclipsing binary during the period 1920 until 2019, with HS Hya being the variable star designation. With a base apparent visual magnitude of 8.08, HS Hya is too dim to be viewed with the naked eye. During the primary eclipse, the magnitude dropped to 8.61; the secondary eclipse lowered the magnitude to 8.55. Based on parallax measurements, the system is located at a distance of approximately 335 light years from the Sun. It is drifting closer with a mean radial velocity of −7 km/s.

TU Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major. It is classified as a Bailey-type 'ab' RR Lyrae variable with a period of 0.557648 days that ranges in brightness from apparent visual magnitude of 9.26 down to 10.24. The distance to this star is approximately 2,090 light years based on parallax measurements. It is located near the north galactic pole at a distance that indicates this is a member of the galactic halo.

TX Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major. With a combined apparent visual magnitude of 6.97, the system is too faint to be readily viewed with the naked eye. The pair orbit each other with a period of 3.063 days in a circular orbit, with their orbital plane aligned close to the line of sight from the Earth. During the primary eclipse, the net brightness decreases by 1.74 magnitudes, while the secondary eclipse results in a drop of just 0.07 magnitude. TX UMa is located at a distance of approximately 780 light years from the Sun based on parallax measurements, but is drifting closer with a mean radial velocity of −13 km/s.

UX Ursae Majoris is an Algol type binary star system in the northern circumpolar constellation of Ursa Major. It is classified as a nova-like variable star similar to DQ Herculis, although no eruptions have been reported. Since its discovery in 1933, this system has been the subject of numerous studies attempting to determine its properties. The combined apparent visual magnitude of UX UMa ranges from 12.57 down to 14.15. The system is located at a distance of approximately 952 light years from the Sun based on parallax, and is drifting further away with a radial velocity of 112 km/s.

XY Ursae Majoris is a short period binary star system in the northern circumpolar constellation of Ursa Major. It is an eclipsing binary with a baseline apparent visual magnitude of 9.50. The system is located at a distance of 221.5 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −10 km/s. It has a relatively high proper motion, traversing the celestial sphere at the angular rate of 0.191″·yr−1.

BZ Ursae Majoris is a dwarf nova star system in the northern circumpolar constellation of Ursa Major. It consists of a white dwarf primary in a close orbit with a red dwarf. The latter star is donating mass, which is accumulating in an accretion disk orbiting the white dwarf. The system is located at a distance of approximately 505 light years from the Sun based on parallax measurements.

SZ Piscium is a suspected triple star system in the equatorial constellation of Pisces. The inner pair form a double-lined spectroscopic binary with an orbital period of 3.966 days. It is a detached Algol-type eclipsing binary of the RS Canum Venaticorum class with a subgiant component. The system is too faint to be readily visible to the naked eye with a combined apparent visual magnitude of 7.18. It is located at a distance of approximately 306 light years based on parallax measurements.

References

  1. 1 2 3 4 5 6 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. Gaia EDR3 record for this source at VizieR.
  2. 1 2 3 4 5 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.
  3. 1 2 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.
  4. 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.
  5. 1 2 3 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.
  6. 1 2 3 4 5 6 7 8 9 10 11 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, 98.
  7. "EQ Tau", SIMBAD , Centre de données astronomiques de Strasbourg , retrieved 2022-03-13.
  8. 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.
  9. Artiukhina, N. M. (1961), "Proper Motions of three W UMa Type Stars in the Pleiades Region", Peremennye Zvezdy (in Russian), Bibcode:1961PZ.....13..366A.
  10. Whitney, B. S. (February 1972), "The Period of EQ Tauri", Information Bulletin on Variable Stars, 633 (1), Bibcode:1972IBVS..633....1W.
  11. Benbow, W. R.; Mutel, R. L. (May 1995), "Eclipse Observations of EQ Tau", Information Bulletin on Variable Stars, 4187 (1), Bibcode:1995IBVS.4187....1B.
  12. 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