109 Tauri


109 Tauri
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 05h 19m 16.60169s[1]
Declination +22° 05′ 47.3740″[1]
Apparent magnitude (V) 4.96[2]
Spectral type G8 III[3]
B−V color index 0.937±0.001[2]
Radial velocity (Rv)+19.03±0.01[4] km/s
Proper motion (μ) RA: +18.91[1] mas/yr
Dec.: −81.57[1] mas/yr
Parallax (π)13.19 ± 0.30[1] mas
Distance247 ± 6 ly
(76 ± 2 pc)
Absolute magnitude (MV)0.56[2]
Mass2.47±0.08 M
Radius8.14±0.46 R
Surface gravity (log g)2.96±0.01 cgs
Temperature5,035±23 K
Metallicity [Fe/H]0.10±0.04 dex
Rotational velocity (v sin i)1.15±0.62 km/s
Age600±50 Myr
Other designations
n Tau, 109 Tau, BD+21° 816, FK5 2398, HD 34559, HIP 24822, HR 1739, SAO 77097[5]
Database references

109 Tauri, or n Tauri, is a single,[6] yellow-hued star in the zodiac constellation of Taurus. It has an apparent visual magnitude of 4.96[2] and is faintly visible to the naked eye. The star has an annual parallax shift of 13.19±0.30 mas,[1] putting it around 247 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.24 due to interstellar dust.[4] It is moving further from the Sun with a heliocentric radial velocity of +19 km/s.[4]

This is an evolved giant star with a stellar classification of G8 III,[3] having consumed the hydrogen at its core and moved off the main sequence. At the age of 600[4] million years, it has become a red clump giant, indicating that it is on the horizontal branch and is generating energy through helium fusion at its core.[7] The star has an estimated 2.47 times the mass of the Sun and has expanded to around eight times the Sun's radius. It is radiating about 60 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,035 K.[4]


  1. ^ a b c d e f van Leeuwen, F. (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 d Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. ^ a b Roman, Nancy G. (July 1952), "The Spectra of the Bright Stars of Types F5-K5", Astrophysical Journal, 116: 122, Bibcode:1952ApJ...116..122R, doi:10.1086/145598.
  4. ^ a b c d e f Jofré, E.; et al. (February 2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: 46, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.
  5. ^ "109 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-22.
  6. ^ 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, S2CID 14878976.
  7. ^ Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society, 408 (2): 1225–1232, arXiv:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x, S2CID 44228180.