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Pi Tauri

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Pi Tauri
Location of π Tauri (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Taurus[1]
Right ascension 04h 26m 36.37093s[2]
Declination +14° 42′ 49.6126″[2]
Apparent magnitude (V) +4.69[3]
Characteristics
Evolutionary stage horizontal branch[4]
Spectral type G7 IIIa Fe-1[5]
U−B color index +0.72[3]
B−V color index +0.98[3]
Astrometry
Radial velocity (Rv)+31.4±0.3[6] km/s
Proper motion (μ) RA: −9.52[2] mas/yr
Dec.: −31.44[2] mas/yr
Parallax (π)7.83±0.22 mas[2]
Distance420 ± 10 ly
(128 ± 4 pc)
Absolute magnitude (MV)−0.84[1]
Details
Mass4.4[7] M☉
Radius22[7] R☉
Luminosity244[8] L☉
Surface gravity (log g)2.39[9] cgs
Metallicity [Fe/H]−0.08[9] dex
Rotational velocity (v sin i)7.1[9] km/s
Age554[10] Myr
Other designations
π Tau, 73 Tau, BD+14°697, HD 28100, HIP 20732, HR 1396, SAO 93935[11]
Database references
SIMBADdata

Pi Tauri (π Tauri) is a solitary,[12] yellow-hued star in the zodiac constellation of Taurus. With an apparent visual magnitude of +4.69,[3] 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,[2] is around 420 light years. At that range, the visual magnitude of the star is diminished by extinction of 0.24 magnitudes due to interstellar dust.[13]

This is an evolved G-type giant star with a stellar classification of G7 IIIa Fe-1,[5] where the suffix notation indicates an underabundance of iron in the spectrum. The measured angular diameter is 1.55±0.06 mas.[14] At the estimated distance of Pi Tauri, this yields a physical size of about 22 times the radius of the Sun.[7] It possesses 4.4 times the mass of the Sun[7] and is radiating 244 times the Sun's luminosity[8] at an effective temperature of 5006 K.[9]

References

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  1. ^ a b 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. XHIP record for this object at VizieR.
  2. ^ 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.
  3. ^ a b c d 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.
  4. ^ Stock, Stephan; Reffert, Sabine; Quirrenbach, Andreas (2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy and Astrophysics. 616: A33. arXiv:1805.04094. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111.
  5. ^ a b 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.
  6. ^ 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.
  7. ^ a b c d Van Belle, Gerard T.; von Braun, Kaspar; Ciardi, David R.; Pilyavsky, Genady; Buckingham, Ryan S.; Boden, Andrew F.; Clark, Catherine A.; Hartman, Zachary; Van Belle, Gerald; Bucknew, William; Cole, Gary (2021). "Direct Measurements of Giant Star Effective Temperatures and Linear Radii: Calibration against Spectral Types and V - K Color". The Astrophysical Journal. 922 (2): 163. arXiv:2107.09205. Bibcode:2021ApJ...922..163V. doi:10.3847/1538-4357/ac1687.
  8. ^ a b Yu, Jie; Khanna, Shourya; Themessl, Nathalie; Hekker, Saskia; Dréau, Guillaume; Gizon, Laurent; Bi, Shaolan (2023). "Revised Extinctions and Radii for 1.5 Million Stars Observed by APOGEE, GALAH, and RAVE". The Astrophysical Journal Supplement Series. 264 (2): 41. arXiv:2206.00046. Bibcode:2023ApJS..264...41Y. doi:10.3847/1538-4365/acabc8.
  9. ^ a b c d Das, Pradosh Barun; Zucker, Daniel B.; De Silva, Gayandhi M.; Borsato, Nicholas W.; Mura-Guzmán, Aldo; Buder, Sven; Ness, Melissa; Nordlander, Thomas; Casey, Andrew R.; Martell, Sarah L.; Bland-Hawthorn, Joss; De Grijs, Richard; Freeman, Ken C.; Kos, Janez; Stello, Dennis; Lewis, Geraint F.; Hayden, Michael R.; Sharma, Sanjib (2025). "The GALAH Survey: Stellar parameters and abundances for 800 000 Gaia RVS spectra using GALAH DR4 and the Cannon". Monthly Notices of the Royal Astronomical Society. 538 (2): 605. arXiv:2410.12272. Bibcode:2025MNRAS.538..605D. doi:10.1093/mnras/staf169.
  10. ^ Ting, Yuan-Sen; Rix, Hans-Walter (2019). "The Vertical Motion History of Disk Stars throughout the Galaxy". The Astrophysical Journal. 878 (1): 21. arXiv:1808.03278. Bibcode:2019ApJ...878...21T. doi:10.3847/1538-4357/ab1ea5.
  11. ^ "pi Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-30.
  12. ^ 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.
  13. ^ 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.
  14. ^ 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.