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Pi Tauri

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Star in the constellation Taurus
Pi Tauri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Taurus
Right ascension 04 26 36.37093
Declination +14° 42′ 49.6126″
Apparent magnitude (V) +4.69
Characteristics
Spectral type G7 IIIa Fe-1
U−B color index +0.72
B−V color index +0.98
Astrometry
Radial velocity (Rv)+31.4±0.3 km/s
Proper motion (μ) RA: −9.52 mas/yr
Dec.: −31.44 mas/yr
Parallax (π)7.83 ± 0.22 mas
Distance420 ± 10 ly
(128 ± 4 pc)
Absolute magnitude (MV)−1.27
Details
Mass3.94 M☉
Radius21 R☉
Luminosity229 L☉
Surface gravity (log g)2.54 cgs
Temperature5,086 K
Metallicity −0.08 dex
Age17 Myr
Other designations
π Tau, 73 Tau, BD+14° 697, HD 28100, HIP 20732, HR 1396, SAO 93935
Database references
SIMBADdata

Pi Tauri (π Tauri) is a solitary, yellow-hued star in the zodiac constellation of Taurus. With an apparent visual magnitude of +4.69, it is bright enough to be visible to the naked eye. Although it appears to lie among the stars of the Hyades cluster, it is not itself a member, being three times farther from Earth than the cluster. The distance to this star, as determined using an annual parallax shift of 7.83 mas as seen from the Earth, is around 420 light years. At that range, the visual magnitude of the star is diminished by an extinction factor of 0.24 due to interstellar dust.

This is an evolved G-type giant star with a stellar classification of G7 IIIa Fe-1, where the suffix notation indicates an underabundance of iron in the spectrum. The measured angular diameter is 1.55±0.06 mas. At the estimated distance of Pi Tauri, this yields a physical size of about 21 times the radius of the Sun. It possesses nearly four times the mass of the Sun and is radiating 229 times the Sun's luminosity at an effective temperature of 5,086 K.

References

  1. ^ 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. ^ Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133 (4): 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
  3. ^ Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  5. ^ Takeda, Yoichi; et al. (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781.
  6. ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
    2 ⋅ R ∗ = ( 127.7 ⋅ 1.55 ⋅ 10 − 3 )   AU 0.0046491   AU / R ⨀ ≈ 42.6 ⋅ R ⨀ {\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(127.7\cdot 1.55\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 42.6\cdot R_{\bigodot }\end{aligned}}}
  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:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  8. "pi Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-30.
  9. 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.
  10. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
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