Tau3 Eridani

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τ3 Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 03h 02m 23.49939s[1]
Declination −23° 37′ 28.0936″[1]
Apparent magnitude (V) 4.10[2]
Spectral type A3 IV-V[3]
U−B color index +0.08[2]
B−V color index +0.16[2]
Radial velocity (Rv) −9.8[4] km/s
Proper motion (μ) RA: −147.25[1] mas/yr
Dec.: −55.28[1] mas/yr
Parallax (π) 36.80 ± 0.18[1] mas
Distance 88.6 ± 0.4 ly
(27.2 ± 0.1 pc)
Mass 1.78[5] M
Radius 1.9[6] R
Luminosity 13.7[7] L
Surface gravity (log g) 4.17[5] cgs
Temperature 8,251±281[5] K
Metallicity [Fe/H] −0.21[3] dex
Rotational velocity (v sin i) 133[8] km/s
Age 476[5] Myr
Other designations
τ3 Eridani, τ3 Eri, 11 Eridani, CD-24° 1387, HD 18978, HIP 14146, HR 919, SAO 168249.[9]
Database references

Tau3 Eridani (τ3 Eri) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.10.[2] Using the parallax method,[1] the distance to this star can be estimated as 88.6 light years. In 2001 it was reported as a candidate Vega-like star, meaning it appears to radiate an infrared excess from an orbiting circumstellar disk.[10] However, this has not been confirmed.[11]

This is an A-type star with a stellar classification of A3 IV-V.[3] The luminosity class of IV-V indicates the spectrum displays traits intermediate between a main sequence and subgiant star. It is around 476[5] million years old and is spinning rapidly with a projected rotational velocity of 133 km/s.[8] This is creating an equatorial bulge that is 7% wider than the polar radius.[12] Tau3 Eridani has 178%[5] of the Sun's mass and nearly double the radius of the Sun.[6] The star shines with 13.7 times the solar luminosity from an outer atmosphere at an effective temperature of 8,251 K.[5]


  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:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b c Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770Freely accessible, Bibcode:2006AJ....132..161G, doi:10.1086/504637. 
  4. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W. 
  5. ^ a b c d e f g David, Trevor J.; Hillenbrand, Lynne A. (May 2015), "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 38, arXiv:1501.03154Freely accessible, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, 146. 
  6. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  7. ^ 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:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ 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/0610785Freely accessible, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224. 
  9. ^ "tau03 Eri -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-10-13. 
  10. ^ Song, Inseok; et al. (January 2001), "Ages of A-Type Vega-like Stars from uvbyβ Photometry", The Astrophysical Journal, 546 (1): 352–357, arXiv:astro-ph/0010102Freely accessible, Bibcode:2001ApJ...546..352S, doi:10.1086/318269. 
  11. ^ Gáspár, András; et al. (May 2013), "The Collisional Evolution of Debris Disks", The Astrophysical Journal, 768 (1): 29, arXiv:1211.1415Freely accessible, Bibcode:2013ApJ...768...25G, doi:10.1088/0004-637X/768/1/25, 25. 
  12. ^ Van Belle, Gerard T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20: 51, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2.