Astronomy:Gamma Tauri

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Short description: Multiple star in the constellation Taurus
γ Tauri
Taurus constellation map.svg
Red circle.svg
Location of γ Tauri (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Taurus
Right ascension  04h 19m 47.6037s[1]
Declination +15° 37′ 39.512″[1]
Apparent magnitude (V) 3.654[2]
Characteristics
Spectral type G8III[3]
U−B color index +0.84[4]
B−V color index +0.99[4]
Astrometry
Radial velocity (Rv)38.7 ± 0.9[5] km/s
Proper motion (μ) RA: +115.29[1] mas/yr
Dec.: -23.86[1] mas/yr
Parallax (π)21.17 ± 1.17[1] mas
Distance154 ± 9 ly
(47 ± 3 pc)
Absolute magnitude (MV)0.22[3]
Details
Mass2.70 ± 0.13[6] M☉
Radius13.4 ± 0.2[7] R☉
Luminosity85[3] L☉
Surface gravity (log g)2.58-2.61[7] cgs
Temperature4,844 ± 47[7] K
Metallicity [Fe/H]+0.11[8] dex
Rotation253 days[9]
Rotational velocity (v sin i)4[10] km/s
Age430–530[3][6] Myr
Other designations
Prima Hyadum, Hyadum I,[11] 54 Tauri, BD+15°612, FK5 159, HD 27371, HIP 20205, HR 1346, SAO 93868, GC 5226, WDS 04198+1538[2]
Database references
SIMBADdata

Gamma Tauri (γ Tauri, abbreviated Gamma Tau, γ Tau) is either a solitary, binary or double star (the Washington Double Star Catalog notes it as a "Dubious Double" or "Bogus Binary"[12]) that marks the tip of the "V" in the constellation of Taurus. It is a member of, and located within about 2.5 parsecs of the center of, the Hyades star cluster, the nearest open cluster to the Sun. Based upon parallax measurements, Gamma Tauri is approximately 154 light-years from the Sun.

Considered as a pair of stars, the two components are designated Gamma Tauri A (officially named Prima Hyadum /ˌpraɪmə ˈhaɪədəm/, the traditional name for the system)[13] and B.

Nomenclature

γ Tauri (Latinised to Gamma Tauri) is the system's Bayer designation. The designations of the two potential components as Gamma Tauri A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[14]

Gamma Tauri bore the traditional name Hyadum I,[11] which is Latin for "First of the Hyades". In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[16] It approved the name Prima Hyadum for the component Gamma Tauri A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[13]

In Chinese, 畢宿 (Bì Xiù), meaning Net, refers to an asterism consisting of Gamma Tauri, Epsilon Tauri, Delta³ Tauri, Delta¹ Tauri, Alpha Tauri (Aldebaran), 71 Tauri and Lambda Tauri.[17] Consequently, the Chinese name for γ Tauri itself is 畢宿四 (Bì Xiù sì), "the Fourth Star of Net".[18]

Properties

Gamma Tauri presents as a spectral class G8 or K0[2][3] giant star with an apparent magnitude of +3.65. This star has passed through the main sequence phase is now a red clump giant, meaning it is using nuclear fusion of helium at its core to provide energy.[19] Age estimates for Gamma Tauri range from 430 million[3] to 530 million years.[6] By comparison, the age of the Hyades cluster is about 625 million years with an error margin of 50 million years.[6]

The angular diameter of this star has been measured using the CHARA array to 2% accuracy. After correcting for limb darkening, this gives the stellar radius as 13.4 times the radius of the Sun.[7] The star is radiating about 85 times the luminosity of the Sun[3] and has 2.7 times the Sun's mass.[6] With its large size and low projected rotational velocity of 4 km s−1,[10] it takes about 253 days to complete a rotation.[9]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Perryman, M. A. C. et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics 323: L49–L52, Bibcode: 1997A&A...323L..49P 
  2. ↑ 2.0 2.1 2.2 "NSV 1553 - Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NSV+1553. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (August 2008). "Stellar Parameters and Elemental Abundances of Late-G Giants". Publications of the Astronomical Society of Japan 60 (4): 781–802. doi:10.1093/pasj/60.4.781. Bibcode: 2008PASJ...60..781T. 
  4. ↑ 4.0 4.1 Johnson, H. L.; Morgan, W. W. (1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". Astrophysical Journal 117: 313–352. doi:10.1086/145697. Bibcode: 1953ApJ...117..313J. 
  5. ↑ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". University of Toronto: International Astronomical Union. Bibcode: 1967IAUS...30...57E. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 da Silva, L. (November 2006). "Basic physical parameters of a selected sample of evolved stars". Astronomy and Astrophysics 458 (2): 609–623. doi:10.1051/0004-6361:20065105. Bibcode: 2006A&A...458..609D. 
  7. ↑ 7.0 7.1 7.2 7.3 Boyajian, Tabetha S. (February 2009). "Angular Diameters of the Hyades Giants Measured with the CHARA Array". The Astrophysical Journal 691 (2): 1243–1247. doi:10.1088/0004-637X/691/2/1243. Bibcode: 2009ApJ...691.1243B. 
  8. ↑ Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (March 2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics 480 (1): 91–101. doi:10.1051/0004-6361:20078788. Bibcode: 2008A&A...480...91S. 
  9. ↑ 9.0 9.1 Setiawan, J. et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics 421: 241–254, doi:10.1051/0004-6361:20041042-1, Bibcode: 2004A&A...421..241S 
  10. ↑ 10.0 10.1 Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago 239 (1): 1. Bibcode: 1970CoAsi.239....1B. 
  11. ↑ 11.0 11.1 Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc.. p. 390. ISBN 0-486-21079-0. 
  12. ↑ "Washington Double Star Catalog". United States Naval Observatory. http://ad.usno.navy.mil/wds/. 
  13. ↑ 13.0 13.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. 
  14. ↑ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  15. ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  16. ↑ "WG Triennial Report (2015-2018) - Star Names". p. 5. https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf. 
  17. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN:978-986-7332-25-7.
  18. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed on line November 23, 2010.
  19. ↑ de Bruijne, J. H. J.; Hoogerwerf, R.; de Zeeuw, P. T. (February 2001). "A Hipparcos study of the Hyades open cluster. Improved colour-absolute magnitude and Hertzsprung-Russell diagrams". Astronomy and Astrophysics 367 (1): 111–147. doi:10.1051/0004-6361:20000410. Bibcode: 2001A&A...367..111D. 



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