EQ Tauri

EQ Tauri

A visual band light curve for EQ Tauri, plotted from ASAS-SN[1] data
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 03h 48m 13.436s[2]
Declination +22° 18′ 50.92″[2]
Apparent magnitude (V) 10.5 (-11.03)[3]
Characteristics
Spectral type G2[4]
Variable type W UMa[3]
Astrometry
Radial velocity (Rv)71.95±1.22[5] km/s
Proper motion (μ) RA: +69.758 mas/yr[2]
Dec.: −30.628 mas/yr[2]
Parallax (π)4.4694 ± 0.0171 mas[2]
Distance730 ± 3 ly
(223.7 ± 0.9 pc)
Orbit[6]
Period (P)0.341348 d
Semi-major axis (a)2.48±0.03 R☉[7]
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
Mass1.22±0.04[7] M☉
Radius1.14±0.01[7] R☉
Luminosity1.32±0.03[7] L☉
Temperature5,800±100[7] K
Secondary
Mass0.54±0.02[7] M☉
Radius0.79±0.01[7] R☉
Luminosity0.63±0.02[7] L☉
Other designations
EQ Tau, TIC 440686937, GSC 01260-00909, 2MASS J03481342+2218509, HV 6189[8]
Database references
SIMBADdata

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.[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]

The star HV 6189 was identified as a short-period variable by H. Shapley and E. M. Hughes in 1940,[9] then was more closely studied by Soviet astronomer V. P. Tsesevich in 1954.[6] It was determined to be a W UMa-type variable and was noted for being located in the region of the Pleiades open cluster.[10] 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.[11] 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.[12] 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.[13]

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]

  1. ^ Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Yuan_Qian_2007 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Bilir_et_al_2005 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Rucinski_et_al_2001 was invoked but never defined (see the help page).
  7. ^ a b c d e f g h i j k Cite error: The named reference Li_et_al_2014 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Shapley_Hughes_1940 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Artiukhina1961 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Whitney1972 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Benbow_Mutel_1995 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Pribulla_Vanko_2002 was invoked but never defined (see the help page).