Astronomy:Theta Doradus

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Short description: Star in the constellation Dorado
Theta Doradus
Location of θ Doradus (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Dorado
Right ascension  05h 13m 45.45571s[1]
Declination −67° 11′ 06.9298″[1]
Apparent magnitude (V) +4.82[2]
Characteristics
Spectral type K2/3 III CNIb/II[3]
U−B color index +1.38[2]
B−V color index +1.28[2]
Astrometry
Radial velocity (Rv)+10.5±0.8[4] km/s
Proper motion (μ) RA: +18.485[1] mas/yr
Dec.: +38.123[1] mas/yr
Parallax (π)6.0186 ± 0.1209[1] mas
Distance540 ± 10 ly
(166 ± 3 pc)
Absolute magnitude (MV)−0.56[5]
Details
Mass2.23[6] M☉
Radius35.6[1] R☉
Luminosity427[6] L☉
Surface gravity (log g)2.5[7] cgs
Temperature4,320±59[6] K
Metallicity [Fe/H]−0.16[5] dex
Rotational velocity (v sin i)2.2[8] km/s
Age1.17[6] Gyr
Other designations
θ Dor, Theta Dor, CPD−67°401, FK5 196, HD 34649, HIP 24372, HR 1744, SAO 249225[9]
Database references
SIMBADdata

Theta Doradus, Latinized from θ Doradus, 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 540 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 CN star, a cool giant showing unusually strong CN bands in its spectrum.[11] With an age of around 1.17 billion years, it has an estimated 2.23 times the mass of the Sun and has expanded to about 36 times the Sun's radius. It is radiating 427 times the solar luminosity from its photosphere at an effective temperature of 4,320 K.[6]

Naming

In the Chinese astronomical adaptation of the European southern hemisphere constellations, 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]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Cousins, A. W. J.; Stoy, R. H. (1962), "Photoelectric magnitudes and colours of Southern stars", Royal Observatory Bulletin 64: 103, Bibcode: 1962RGOB...64..103C. 
  3. ↑ 3.0 3.1 Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H. 
  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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D. 
  5. ↑ 5.0 5.1 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. ↑ 6.0 6.1 6.2 6.3 6.4 Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal 150 (3): 23, doi:10.1088/0004-6256/150/3/88, 88, Bibcode: 2015AJ....150...88L. 
  7. ↑ 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, doi:10.1111/j.1365-2966.2009.14917.x, Bibcode: 2009MNRAS.397..335Z. 
  8. ↑ De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014), "A catalog of rotational and radial velocities for evolved stars. V. Southern stars", Astronomy and Astrophysics 561: A126, doi:10.1051/0004-6361/201220762, Bibcode: 2014A&A...561A.126D. 
  9. ↑ "tet Dor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tet+Dor. 
  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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  11. ↑ Gray, C. Richard O.; Corbally, J. (2009), Stellar Spectral Classification, Princeton University Press, p. 278, ISBN 978-0691125114. 
  12. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 27 日



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