Theta Doradus

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Theta Doradus
Diagram showing star positions and boundaries of the Dorado constellation and its surroundings
Cercle rouge 100%.svg
Location of θ Doradus (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Dorado
Right ascension 05h 13m 45.45566s[1]
Declination −67° 11′ 06.9305″[1]
Apparent magnitude (V) +4.82[2]
Spectral type K2/3 III CNIb/II[3]
U−B color index +1.38[2]
B−V color index +1.28[2]
Radial velocity (Rv)+10.5±0.8[4] km/s
Proper motion (μ) RA: +19.19[1] mas/yr
Dec.: +37.55[1] mas/yr
Parallax (π)6.64 ± 0.15[1] mas
Distance490 ± 10 ly
(151 ± 3 pc)
Absolute magnitude (MV)−0.56[5]
Mass2.23[6] M
Radius16[7] R
Luminosity426.6[6] L
Surface gravity (log g)2.5[8] cgs
Temperature4,320±59[6] K
Metallicity [Fe/H]−0.16[5] dex
Age1.17[6] Gyr
Other designations
θ Dor, CPD−67° 401, FK5 196, HD 34649, HIP 24372, HR 1744, SAO 249225[9]
Database references

Theta Doradus (Theta Dor, θ Doradus, θ Dor) is a solitary[10] star in the southern constellation of Dorado. Based upon an annual parallax shift of 6.64 mas as seen from Earth, it is located around 490 light years from the Sun. With an apparent visual magnitude of +4.82,[2] the star is bright enough to be faintly visible to the naked eye.

This is an evolved orange-hued K-type giant star with a stellar classification of K2/3 III CNIb/II,[3] where the suffix indicates it is a chemically peculiar star with a strong CN band.[11] With an age of around 1.17 billion years,[6] it has an estimated 2.23[6] times the mass of the Sun and has expanded to about 16[7] times the Sun's radius. It is radiating 426.6 times the solar luminosity from its photosphere at an effective temperature of 4,320 K.[6]


In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 夾白 (Jiá Bái), meaning White Patches Attached, refers to an asterism consisting of θ Doradus and α Reticuli. Consequently, θ Doradus itself is known as 夾白一 (Jiá Bái yī, English: the First Star of White Patches Attached.)[12]


  1. ^ a b c d e 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 Cousins, A. W. J.; Stoy, R. H. (1962), "Photoelectric magnitudes and colours of Southern stars", Royal Observatory Bulletin, 64, Bibcode:1962RGOB...64..103C. 
  3. ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, 
  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:1208.3048Freely accessible, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ a b Flynn, C.; Mermilliod, J.-C. (October 1991), "On the DDO absolute magnitudes of K giants", Astronomy and Astrophysics, 250 (2): 400–406, Bibcode:1991A&A...250..400F. 
  6. ^ a b c d e f g Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466Freely accessible, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, 88. 
  7. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  8. ^ Zboril, M. (July 2009), "Metallicity and photospheric abundances in field GKM giants and dwarfs", Monthly Notices of the Royal Astronomical Society, 397 (1): 335–340, Bibcode:2009MNRAS.397..335Z, doi:10.1111/j.1365-2966.2009.14917.x. 
  9. ^ "tet Dor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-14. 
  10. ^ 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  11. ^ Gray, C. Richard O.; Corbally, J. (2009), Stellar Spectral Classification, Princeton University Press, p. 278, ISBN 0691125112. 
  12. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 27 日