Kappa Tauri

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Kappa Tauri
Observation data
Epoch J2000.0      Equinox
Constellation Taurus
κ¹ Tau
Right ascension 04h 25m 22.16505s[1]
Declination +22° 17′ 37.9375″[1]
Apparent magnitude (V) +4.22[2]
κ² Tau
Right ascension 04h 25m 25.01518s[1]
Declination +22° 11′ 59.9876″[1]
Apparent magnitude (V) +5.24[2]
κ¹ Tau
Spectral type A7IV-V[3]
U−B color index +0.12[2]
B−V color index +0.14[2]
Variable type δ Scuti[4]
κ² Tau
Spectral type A7V
U−B color index +0.09[2]
B−V color index +0.17[2]
Variable type δ Scuti[4]
κ¹ Tau
Radial velocity (Rv) +37.30[5] km/s
Proper motion (μ) RA: +105.10[1] mas/yr
Dec.: −45.04[1] mas/yr
Parallax (π) 21.19 ± 0.21[1] mas
Distance 154 ± 2 ly
(47.2 ± 0.5 pc)
κ² Tau
Radial velocity (Rv) +32.00[6] km/s
Proper motion (μ) RA: +111.97[1] mas/yr
Dec.: −47.71[1] mas/yr
Parallax (π) 22.03 ± 0.35[1] mas
Distance 148 ± 2 ly
(45.4 ± 0.7 pc)
κ¹ Tau
Radius 2.60[7] R
Luminosity 33.6[8] L
Temperature 9,000[7] K
Rotational velocity (v sin i) 94[9] km/s
κ² Tau
Luminosity 11.8[8] L
Temperature 7,400[8] K
Rotational velocity (v sin i) 191[9] km/s
Other designations
κ Tau, ADS 3201
κ¹ Tau: 65 Tauri, BD+21 642, HD 27934, HIP 20635, HR 1387, SAO 76601.[10]
κ² Tau: 67 Tauri, BD+21 643, HD 27946, HIP 20641, HR 1388, SAO 76602.[11]

Kappa Tauri (κ Tau, κ Tauri) is a double star in the constellation Taurus and a member of the Hyades open cluster.[4] The pair are approximately 150 light years from Earth, but are separated by about six light years.[1]

The system is dominated by a visual double star, κ¹ Tauri and κ² Tauri. κ¹ Tauri is a white A-type subgiant with an apparent magnitude of +4.22.[2] It is emitting an excess of infrared radiation at a temperature indicating there is a circumstellar disk in orbit at a radius of 67 AU from the star.[7] κ² Tauri is a white A-type main sequence star with an apparent magnitude of +5.24.[2] Both stars are Delta Scuti variables.[4]

Between the two bright stars is a binary star made up of two 9th magnitude stars, Kappa Tauri C and Kappa Tauri D, which are 5.5 arcseconds from each other (as of 2013) and 175.1 arcseconds from κ¹ Tau. Two more 12th magnitude companions fill out the visual group: Kappa Tauri E, which is 145 arcseconds from κ¹ Tau, and Kappa Tauri F, 108.5 arcseconds away from κ² Tau.[12]

Kappa Tauri was photographed during Solar eclipse of May 29, 1919 by the expedition of Arthur Eddington in Príncipe and others in Sobral, Brazil that confirmed Albert Einstein's prediction of the bending of light around the Sun from his general theory of relativity which he published in 1915.[13]


  1. ^ a b c d e f g h i j k van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e f g h Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data. SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819 
  4. ^ a b c d Horan, S. (November 1979), "A photometric survey of the Hyades for Delta Scuti variables", Astronomical Journal, 84: 1770−1774, Bibcode:1979AJ.....84.1770H, doi:10.1086/112607 
  5. ^ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065. 
  6. ^ Kharchenko, N. V.; et al. (2007), "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations", Astronomische Nachrichten, 328 (9): 889, arXiv:0705.0878free to read, Bibcode:2007AN....328..889K, doi:10.1002/asna.200710776. 
  7. ^ a b c Rhee, Joseph H.; et al. (May 2007), "Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs", The Astrophysical Journal, 660 (2): 1556−1571, arXiv:astro-ph/0609555free to read, Bibcode:2007ApJ...660.1556R, doi:10.1086/509912. 
  8. ^ a b c McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037free to read, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  9. ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785free to read, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224. 
  10. ^ "kap01 Tau -- Variable Star of delta Sct type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2015-11-05. 
  11. ^ "kap02 Tau -- Variable Star of delta Sct type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2015-11-05. 
  12. ^ Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-11-08 
  13. ^ Dyson, F.W.; Eddington, A.S.; Davidson, C.R. (1920). "A Determination of the Deflection of Light by the Sun's Gravitational Field, from Observations Made at the Solar eclipse of May 29, 1919". Phil. Trans. Roy. Soc. A. 220 (571-581): 291–333. Bibcode:1920RSPTA.220..291D. doi:10.1098/rsta.1920.0009.