41 Tauri


41 Tauri
The Baby Eagle Nebula LBN777.jpg
41 Tauri is the brightest star on the right of the molecular cloud LBN 777.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 04h 06m 36.41237s[1]
Declination +27° 35′ 59.6317″[1]
Apparent magnitude (V) 5.19[2]
Spectral type B9 p Si[3]
U−B color index −0.47[2]
B−V color index −0.12[2]
Variable type α² CVn[4]
Radial velocity (Rv)−2.0[5] km/s
Proper motion (μ) RA: +21.88[1] mas/yr
Dec.: −52.34[1] mas/yr
Parallax (π)7.76 ± 0.36[1] mas
Distance420 ± 20 ly
(129 ± 6 pc)
Period (P)7.2274 d
Eccentricity (e)0.18
Semi-amplitude (K1)
16.60 km/s
Mass2.9[6] M
Radius3.54[7] R
Luminosity190[8] L
Surface gravity (log g)3.87[9] cgs
Temperature12,600[9] K
Metallicity [Fe/H]0.43[9] dex
Other designations
BD+27° 633, HD 25823, HIP 19171, HR 1268, SAO 76455.[10]
Database references

41 Tauri is the Flamsteed designation for a single-lined spectroscopic binary system in the zodiacal constellation of Taurus. The star has a visual magnitude of 5.19,[2] making it visible to the naked eye from brighter suburban skies (according to the Bortle scale). Parallax measurements with the Hipparcos spacecraft put it at a distance of roughly 420 light-years (129 parsecs) from the Sun.[1]

This is a chemically peculiar star and was first classified as a silicon star by American astronomer William Morgan in 1933. The stellar spectrum displays an overabundance of heavier elements;[9] particularly silicon and gallium. These abundances may be caused by the magnetic field of the star, which produces concentrations of the observed elements in the outer atmosphere.[11] It is a α² Canum Venaticorum-type variable star, ranging in magnitude from 5.15 down to 5.22. These variations are likely due to large spots or rings on the side of the star being observed.[4]

The star and its companion orbit each other closely with a period of a week and an eccentricity of 0.18. The rotation period of the primary star has become locked to its orbit, so that one face is always pointed toward its companion. The abundance of gallium and silicon varies in a sinusoidal pattern that matches this period.[11]

The primary has around 2.9[6] times the mass of the Sun, 3.5[7] times the Sun's radius, and is emitting 190[8] the luminosity of the Sun. The effective temperature of the star's photosphere is 12,600 K,[9] giving it the blue-white hue of a B-type star.[12]


  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 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 Kukarkin, B. V.; et al. (1971), General Catalogue of Variable Stars (3rd ed.), Bibcode:1971GCVS3.C......0K.
  5. ^ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington, D. C.: Carnegie Institute of Washington., Bibcode:1953GCRV..C......0W.
  6. ^ a b c Ducati, J. R.; et al. (January 2011), "The mass ratio and initial mass functions in spectroscopic binaries" (PDF), Astronomy and Astrophysics, 525: 9, Bibcode:2011A&A...525A..26D, doi:10.1051/0004-6361/200913895, A26.
  7. ^ a b Shulyak, D.; et al. (September 2014), "Interferometry of chemically peculiar stars: theoretical predictions versus modern observing facilities", Monthly Notices of the Royal Astronomical Society, 443 (2): 1629–1642, arXiv:1406.6093, Bibcode:2014MNRAS.443.1629S, doi:10.1093/mnras/stu1259.
  8. ^ a b 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:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  9. ^ a b c d e Bolcal, C.; et al. (December 1987), "A model atmosphere analysis of HD 25823", Astrophysics and Space Science, 139 (2): 295–304, Bibcode:1987Ap&SS.139..295B, doi:10.1007/BF00644358, S2CID 121253643.
  10. ^ "41 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-11-09.{{cite web}}: CS1 maint: postscript (link)
  11. ^ a b Artru, M.-C.; Freire-Ferrero, R. (September 1988), "Line variations in the ultra-violet spectrum of the Ap-Si star HD 25823", Astronomy and Astrophysics, 203 (1): 111–116, Bibcode:1988A&A...203..111A.
  12. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16.