Theta Draconis

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]

θ Draconis
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]
Characteristics
Spectral type F9 V[1]
U−B color index +0.11[3]
B−V color index +0.53[3]
Astrometry
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]
Details
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
SIMBADdata

Chinese name

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, the Chinese name for θ Draconis itself is 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]

Properties

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]

References
  1. "tet Dra -- Spectroscopic binary". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-11-21.
  2. van Leeuwen, F. (November 2007). "Hipparcos, the New Reduction". Astronomy and Astrophysics. Centre de Données astronomiques de Strasbourg. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Retrieved 2010-11-21.
  3. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished) origin=SIMBAD". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  4. Kaler, James B. "THETA DRA (Theta Draconis)". Stars. University of Illinois. Retrieved 2010-11-21.
  5. 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/0308294, 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

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