111 Tauri

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111 Tauri
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 05h 24m 25.46380s[1]
Declination +17° 23′ 00.7166″[1]
Apparent magnitude (V) 5.1149[1]
Spectral type F8 V + K5 V[2]
U−B color index −0.05[3]
B−V color index 0.544[1]
Variable type BY Dra[3]
Radial velocity (Rv) +37.8[4] km/s
Proper motion (μ) RA: +251.05[1] mas/yr
Dec.: −7.99[1] mas/yr
Parallax (π) 69.51 ± 0.38[1] mas
Distance 46.9 ± 0.3 ly
(14.39 ± 0.08 pc)
Absolute magnitude (MV) 3.49 ± 0.06[5]
111 Tau A
Mass 1.08[5] M
Radius 1.67 ± 0.06[5] R
Luminosity 1.845[6] L
Surface gravity (log g) 4.24[7] cgs
Temperature 6,015[7] K
Metallicity [Fe/H] −0.14[7] dex
Rotation 4.1 days[8]
Rotational velocity (v sin i) 16.0[9] km/s
Age 3.76[10] Gyr
Other designations
111 Tau, GJ 202, HR 1780, BD+17 920, HD 35296, LTT 11642, SAO 94526, HIP 25278.[3]

111 Tauri is a wide binary star[2] system in the constellation Taurus. It is located at a distance of about 47 light years from the Sun. Primary component A is a main sequence star with a stellar classification of F8V. The secondary component B (Gliese 201) is a K-type main sequence star.[2] It is larger and more luminous than the Sun, with about 130% of the Sun's radius and 185% of the Sun's luminosity. The apparent magnitude of 5.1 indicates it is a faint star that can be viewed by the naked eye under good, dark-sky conditions.

The metallicity of the primary star, which measures the proportion of elements other than hydrogen and helium, is similar to the Sun. Estimates of [Fe/H], which is the logarithm of the ratio of iron to hydrogen as compared to the Sun, range from a low of −0.14 to a high of 0.05.[7][8] This star shows an unusually high content of Lithium, which remains unexplained.[8] Age estimates for this star range from 3.6 to 3.76 billion years.[4][10] It is a prominent X-ray source.[8]

This star is rotating relatively rapidly, completing a rotation along the equator every 4.1 days as compared to 25 days for the Sun. It is also undergoing differential rotation in which the rotation velocity varies by latitude.[11]

This star was examined for an excess of infrared emission that could indicate it has a circumstellar debris disk of dust, but no significant excess was observed.[10] The space velocity components of this star are [U, V, W] = [−36.94, −14.63, 7.63] km/s.[12] It shares a common proper motion with HIP 25220, an active star with stellar classification K4V. Both stars are members of the Hyades stellar kinematic group of co-moving stars.[8]


  1. ^ a b c d e f g van Leeuwen, F. (November 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. 
  2. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. 
  3. ^ a b c "V* V1119 Tau -- Variable of BY Dra". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2011-07-03. 
  4. ^ a b Holmberg, J.; Nordstrom, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics 501 (3): 941−947. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. 
  5. ^ a b c Fuhrmann, Klaus (February 2008), "Nearby stars of the Galactic disc and halo - IV", Monthly Notices of the Royal Astronomical Society 384 (1): 173–224, Bibcode:2008MNRAS.384..173F, doi:10.1111/j.1365-2966.2007.12671.x 
  6. ^ Takeda, Yoichi (April 2007). "Fundamental Parameters and Elemental Abundances of 160 F-G-K Stars Based on OAO Spectrum Database". Publications of the Astronomical Society of Japan 59 (2): 335–356. Bibcode:2007PASJ...59..335T. 
  7. ^ a b c d Chen, Y. Q.; Nissen, P. E.; Zhao, G.; Zhang, H. W.; Benoni, T. (February 2000). "Chemical composition of 90 F and G disk dwarfs". Astronomy and Astrophysics Supplement 141: 491−506. arXiv:astro-ph/9912342. Bibcode:2000A&AS..141..491C. doi:10.1051/aas:2000124. 
  8. ^ a b c d e Makarov, V. V.; Zacharias, N.; Hennessy, G. S. (November 2008). "Common Proper Motion Companions to Nearby Stars: Ages and Evolution". The Astrophysical Journal 687 (1): 566−578. arXiv:0808.3414. Bibcode:2008ApJ...687..566M. doi:10.1086/591638. 
  9. ^ Schröder, C.; Reiners, A.; Schmitt, J. H. M. M. (January 2009). "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo". Astronomy and Astrophysics 493 (3): 1099−1107. Bibcode:2009A&A...493.1099S. doi:10.1051/0004-6361:200810377. 
  10. ^ a b c Trilling, D. E.; et al (February 2008). "Debris Disks around Sun-like Stars". The Astrophysical Journal 674 (2): 1086−1105. arXiv:0710.5498. Bibcode:2008ApJ...674.1086T. doi:10.1086/525514. 
  11. ^ Reiners, A. (January 2006). "Rotation- and temperature-dependence of stellar latitudinal differential rotation". Astronomy and Astrophysics 446 (1): 267–277. arXiv:astro-ph/0509399. Bibcode:2006A&A...446..267R. doi:10.1051/0004-6361:20053911. 
  12. ^ Montes, D.; et al (November 2001). "Late-type members of young stellar kinematic groups - I. Single stars". Monthly Notices of the Royal Astronomical Society 328 (1): 45–63. arXiv:astro-ph/0106537. Bibcode:2001MNRAS.328...45M. doi:10.1046/j.1365-8711.2001.04781.x.