Theta Draconis

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Theta Draconis
Diagram showing star positions and boundaries of the Draco constellation and its surroundings
Cercle rouge 100%.svg
Location of θ Draconis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 16h 01m 53.3457s[1]
Declination +58° 33′ 54.905″[1]
Apparent magnitude (V) 4.1190[2]
Spectral type F9 V[1]
U−B color index +0.11[3]
B−V color index +0.53[3]
Radial velocity (Rv)-8.5[1] km/s
Proper motion (μ) RA: -319.51[2] mas/yr
Dec.: 334.97[2] mas/yr
Parallax (π)47.54 ± 0.12[2] mas
Distance68.6 ± 0.2 ly
(21.03 ± 0.05 pc)
Absolute magnitude (MV)2.50[2]
Mass1.21[4] M
Radius2.5[4] R
Luminosity8.7[5] L
Surface gravity (log g)4.13[5] cgs
Temperature6,290[4] K
Metallicity [Fe/H]+0.20[5] dex
Rotational velocity (v sin i)27[6] km/s
Age3.1[7] Gyr
Other designations
θ Dra, 13 Her, BD+58° 1608, FK5 598, HD 144284, HIP 78527, HR 5986, SAO 29765.
Database references

Theta Draconis (θ Dra / θ Draconis) is a fourth-magnitude star in the northern circumpolar constellation of Draco. Parallax measurements place it at an estimated distance of 68.6 light-years (21.0 parsecs) from Earth.[2]

This star is 21% more massive than the Sun and has a radius 2.5 times the Sun's.[4] It is radiating 8.7 times the luminosity of the Sun[5] from its outer atmosphere at an effective temperature of 6,290 K.[4] This temperature is what gives it the yellow-white hue of an F-type main sequence star with a stellar classification of F9 V.[1]

Chinese name[edit]

In Chinese, 紫微左垣 (Zǐ Wēi Zuǒ Yuán), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of θ Draconis, ι Draconis, η Draconis, ζ Draconis, υ Draconis, 73 Draconis, γ Cephei and 23 Cassiopeiae.[8] Consequently, θ Draconis itself is known as 紫微左垣二 (Zǐ Wēi Zuǒ Yuán èr, English: the Second Star of Left Wall of Purple Forbidden Enclosure.),[9] representing 上宰 (Shǎngzǎi), meaning The First Premier.[10] 上宰 (Shǎngzǎi) is westernized into Shang Tsae by R.H. Allen with meaning "the Minor Steward" but it was for η Dra (Aldibain)[11]

See also[edit]


  1. ^ a b c d e "tet Dra -- Spectroscopic binary". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-11-21. 
  2. ^ a b c d e f van Leeuwen, F. (November 2007). "Hipparcos, the New Reduction". Astronomy and Astrophysics. Centre de Données astronomiques de Strasbourg. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Retrieved 2010-11-21. 
  3. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished) origin=SIMBAD". Catalogue of Eggen's UBV data (PDF). Bibcode:1986EgUBV........0M. 
  4. ^ a b c d e Kaler, James B. "THETA DRA (Theta Draconis)". Stars. University of Illinois. Retrieved 2010-11-21. 
  5. ^ a b c d Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M 
  6. ^ Hoffleit; et al. (1991). "Bright Star Catalogue". VizieR (5th Revised ed.). Centre de Données astronomiques de Strasbourg. Retrieved 2010-11-21. 
  7. ^ Decin, G.; et al. (November 2003), "Age Dependence of the Vega Phenomenon: Observations", The Astrophysical Journal, 598 (1): 636–644, arXiv:astro-ph/0308294Freely accessible, Bibcode:2003ApJ...598..636D, doi:10.1086/378800 
  8. ^ (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.
  9. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 10 日
  10. ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived 2008-09-24 at the Wayback Machine., Hong Kong Space Museum. Accessed on line November 23, 2010.
  11. ^ Star Name - R.H. Allen p. 210

External links[edit]

Coordinates: Sky map 16h 01m 53.35s, +58° 33′ 54.90″