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8 Draconis

From Wikipedia, the free encyclopedia
White-hued chemically unusual star in the constellation Draco
8 Draconis
Location of 8 Draconis (circled in red)
Observation data
EpochJ2000.0      EquinoxJ2000.0 (ICRS)
ConstellationDraco
Right ascension12h 55m 28.54856s[1]
Declination+65° 26′ 18.5071″[1]
Apparent magnitude (V)5.225[2]
Characteristics
Evolutionary stagemain sequence[1]
Spectral typeF1VmA7(n)[3]
B−Vcolor index0.303±0.005[4]
Variable typeGamma Doradus[5]
Astrometry
Radial velocity (Rv)+9.0[6] km/s
Proper motion (μ)RA: −3.658[1]mas/yr
Dec.: −30.126[1]mas/yr
Parallax (π)33.9667±0.0792 mas[1]
Distance96.0 ± 0.2 ly
(29.44 ± 0.07 pc)
Absolute magnitude (MV)2.90[4]
Details
Mass1.56[7] M☉
Radius1.50[7] R☉
Luminosity5.75[4] L☉
Surface gravity (log g)4.01[3] cgs
Temperature7,129[3] K
Metallicity[Fe/H]−0.14[3] dex
Rotational velocity (v sin i)119.6[8] km/s
Age250±200[7] Myr
Other designations
Taiyi,8 Dra,IR Draconis,BD+66°778,FK5 486,HD 112429,HIP 63076,HR 4916,SAO 15941[9]
Database references
SIMBADdata

8 Draconis, formally namedTaiyi/ˌtaɪˈjiː/,[10] is a single[11]star in the northerncircumpolar constellation ofDraco. Based upon an annualparallax shift of33.97 mas as seen from theEarth,[12] the star is located 96 light-years from theSun. It is moving further away with a heliocentricradial velocity of +9 km/s,[6] having come within 40.6 ly some 2.6 million years ago.[4]

Alight curve for IR Draconis, adapted from Aertset al. (1998)[13]

This is anF-type main-sequence star with astellar classification of F1VmA7(n).[3] It is aGamma Doradus variable star with a brightness variation of about one tenth of amagnitude.[5] 8 Dra has a relatively high rate of rotation, showing aprojected rotational velocity of 120 km/s.[8] The star has 1.56 times themass of the Sun and 1.50 times theSun's radius.[7] It is radiating 5.75[4] times theSun's luminosity from itsphotosphere at aneffective temperature of 7,129 K.[3] Aninfrared excess has been detected atwavelengths of 24 and 70μm, which suggests the presence of acircumstellar disk orbiting the star.[7]

Nomenclature

[edit]

8 Draconis is the star'sFlamsteed designation. It also received thevariable star designation IR Draconis in 2000, after its variability had been discovered usingHipparcos photometry.[5]

The star bore thetraditional Chinese name ofTaiyi,[14][15] from 太乙 (Tài Yǐ) or 太一 (Tài Yī, the Great One), both of which refer toTao. Alternatively, Taiyi may refer toHD 119476[17] or4 Draconis,[18] with7 and 8 Draconis formingNeichu, representing a private kitchen.[19] In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[20] to catalogue and standardize proper names for stars. The WGSN approved the nameTaiyi for this star on 30 June 2017 and it is now so entered in the IAU Catalog of Star Names.[21]

References

[edit]
  1. ^abcdefVallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties".Astronomy and Astrophysics.674: A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID 244398875. Gaia DR3 record for this source atVizieR.
  2. ^Høg, E; Fabricius, C; Makarov, V. V; Urban, S; Corbin, T; Wycoff, G; Bastian, U; Schwekendiek, P; Wicenec, A (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars".Astronomy and Astrophysics.355: L27.Bibcode:2000A&A...355L..27H.
  3. ^abcdefGray, R. O; Corbally, C. J; Garrison, R. F; McFadden, M. T; Robinson, P. E (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I".The Astronomical Journal.126 (4): 2048.arXiv:astro-ph/0308182.Bibcode:2003AJ....126.2048G.doi:10.1086/378365.S2CID 119417105.
  4. ^abcdeAnderson, 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,S2CID 119257644.
  5. ^abcSamus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)".VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S.1.Bibcode:2009yCat....102025S.
  6. ^abWilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities".Washington.Bibcode:1953GCRV..C......0W.
  7. ^abcdePlavchan, Peter; et al. (2009), "New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope",The Astrophysical Journal,698 (2):1068–94,arXiv:0904.0819,Bibcode:2009ApJ...698.1068P,doi:10.1088/0004-637X/698/2/1068,S2CID 51417657.
  8. ^abSchröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009),"Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo"(PDF),Astronomy and Astrophysics,493 (3):1099–1107,Bibcode:2009A&A...493.1099S,doi:10.1051/0004-6361:200810377[permanent dead link]
  9. ^"8 Dra".SIMBAD.Centre de données astronomiques de Strasbourg. Retrieved2019-01-23.
  10. ^"The Sky Live".theskylive.com. Retrieved2025-04-09.
  11. ^Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems",Monthly Notices of the Royal Astronomical Society,389 (2): 869,arXiv:0806.2878,Bibcode:2008MNRAS.389..869E,doi:10.1111/j.1365-2966.2008.13596.x,S2CID 14878976.
  12. ^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.
  13. ^Aerts, C.; Eyer, L.; Kestens, E. (September 1998). "The discovery of new γ Doradus stars from the HIPPARCOS mission".Astronomy and Astrophysics.337:790–796.Bibcode:1998A&A...337..790A.
  14. ^Bonnet-Bidaud, Jean-Marc; Praderie, Françoise; Whitfield, Susan (March 2009). "The Dunhuang Chinese sky: A comprehensive study of the oldest known star atlas".Journal of Astronomical History and Heritage.12 (1):39–59.arXiv:0906.3034.Bibcode:2009JAHH...12...39B.doi:10.3724/SP.J.1440-2807.2009.01.04.
  15. ^"WG Triennial Report (2015-2018) - Star Names"(PDF). p. 7. Retrieved2018-07-14.
  16. ^Yi, Shitong (April 1981).中西对照恒星图表 [Atlas Comparing Chinese and Western Star Maps and Catalogues] (in Chinese). 科学出版社.
  17. ^Stellarium, citing Yi Shitong, 1981[16]
  18. ^Yang, Bo-Shun; Hoffmann, Susanne M. (December 2024). "Identification of Z Cam's Historical Counterpart: The Quest for an Ancient Nova".Research in Astronomy and Astrophysics.24 (12): 125004.arXiv:2410.19010.Bibcode:2024RAA....24l5004Y.doi:10.1088/1674-4527/ad89aa.
  19. ^Ridpath, Ian."Star Tales - Draco". Retrieved10 May 2025.
  20. ^"International Astronomical Union | IAU".www.iau.org. Retrieved2025-04-09.
  21. ^"IAU Catalog of Star Names". Retrieved10 May 2025.


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