47 Tauri


47 Tauri (abbreviated to 47 Tau) is a binary star in the zodiac constellation of Taurus. Parallax measurements made by the Hipparcos spacecraft put it at a distance of about 330 light-years (102 parsecs) from Earth. The system has a combined apparent magnitude of about 4.89,[2] meaning it can be faintly seen with the naked eye, according to the Bortle scale.

47 Tauri
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 04h 13m 56.38482s[1]
Declination +09° 15′ 49.7729″[1]
Apparent magnitude (V) 4.89[2]
(5.05 + 7.32)[3]
Spectral type G5III + A7V:[4]
U−B color index +0.46[5]
B−V color index +0.82[5]
Radial velocity (Rv)-8.2 ± 0.4[6] km/s
Proper motion (μ) RA: -10.31[1] mas/yr
Dec.: -30.01[1] mas/yr
Parallax (π)9.83 ± 0.64 mas[1]
Distance330 ± 20 ly
(102 ± 7 pc)
Period (P)479 yr
Semi-major axis (a)1.053″
Eccentricity (e)0.910
Inclination (i)128.6°
Longitude of the node (Ω)52.9°
Periastron epoch (T)B 1816.6
Argument of periastron (ω)
47 Tau A
Radius12.9[7] R
Surface gravity (log g)2.67 ± 0.11[6] cgs
Temperature5117 ± 58[6] K
Metallicity [Fe/H]-0.10 ± 0.08[6] dex
Other designations
BD+08° 652, HD 26722, HIP 19740, HR 1311, SAO 111674
Database references
47 Tau A
47 Tau B

47 Tauri is a visual binary, meaning that the two components can be resolved, and the orbit is derived from the positions of the two stars. The primary component is a G-type giant. Its radius is about 13 times that of the Sun.[7] The companion is likely a white-colored A-type main-sequence star that is fainter. The two stars are separated about 1.3 arcseconds away,[2] and because of their large separation, the two stars take some 479 years to complete an orbit.[3]


  1. ^ a b c d e van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b c "* 47 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 May 2017.
  3. ^ a b c "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 2 May 2017.
  4. ^ Stephenson, C. B.; Sanwal, N. B. (1969). "The masses of stars above the main sequence". The Astronomical Journal. 74: 689. Bibcode:1969AJ.....74..689S. doi:10.1086/110845.
  5. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. ^ a b c d Kang, Wonseok; Lee, Sang-Gak; Kim, Kang-Min (2011). "Abundances of Refractory Elements for G-Type Stars with Extrasolar Planets". The Astrophysical Journal. 736 (2): 87. arXiv:1105.3083. Bibcode:2011ApJ...736...87K. doi:10.1088/0004-637X/736/2/87. S2CID 118382154.
  7. ^ a b Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy & Astrophysics. 367 (2): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.