Theta Centauri

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Theta Centauri
Diagram showing star positions and boundaries of the Centaurus constellation and its surroundings
Cercle rouge 100%.svg

Location of θ Centauri (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 14h 06m 40.94752s[1]
Declination –36° 22′ 11.8371″[1]
Apparent magnitude (V) +2.06[2]
Characteristics
Spectral type K0 III[3]
U−B color index +0.90[2]
B−V color index +0.99[2]
Astrometry
Radial velocity (Rv) +1.3[4] km/s
Proper motion (μ) RA: –520.53[1] mas/yr
Dec.: –518.06[1] mas/yr
Parallax (π) 55.45 ± 0.20[1] mas
Distance 58.8 ± 0.2 ly
(18.03 ± 0.07 pc)
Absolute magnitude (MV) 0.87[5]
Details
Radius 10.6[6] R☉
Luminosity 60[7] L☉
Surface gravity (log g) 2.75[8] cgs
Temperature 4,980[8] K
Metallicity [Fe/H] 0.03[8] dex
Other designations
Menkent, Haratan, 5 Centauri, CD−35 9260, FK5 520, Gl 539, HD 123139, HIP 68933, HR 5288, LHS 2858, SAO 205188.[9]

Theta Centauri (θ Cen, θ Centauri) is a star in the southern constellation of Centaurus, the centaur. It has the traditional Arabic name Menkent (possibly abbreviation of ألمنكب ألقنتوس - al mankib al-qanturis, meaning "shoulder of the Centaur"). This star has an apparent visual magnitude of +2.06,[2] making it the fourth brightest member of the constellation. This star is close enough to the Earth that its distance can be measured using the parallax technique, yielding a value of 58.8 light-years (18.0 parsecs).[1]

In Chinese, 庫樓 (Kù Lóu), meaning Arsenal, refers to an asterism consisting of θ Centauri, ζ Centauri, η Centauri, 2 Centauri, HD 117440, ξ1 Centauri, γ Centauri, τ Centauri, D Centauri and σ Centauri.[10] Consequently, θ Centauri itself is known as 庫樓三 (Kù Lóu sān, English: the Third Star of Arsenal.)[11]

This is an evolved giant star with a stellar classification of K0 III.[3] The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 5.46 ± 0.06 mas,[12] which, at its estimated distance, equates to a physical radius of about 10.6 times the radius of the Sun.[6] The outer envelope has an effective temperature of 4,980 K,[8] giving it the orange-hued glow of a cool, K-type star.[13] Soft X-ray emission has been detected from this star, which has an estimated X-ray luminosity of 1.4 × 1027 erg s−1.[14]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.. The radius (R*) is given by:
    \begin{align} 2\cdot R_* & = \frac{(18.03\cdot 5.46\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 21.2\cdot R_{\bigodot} \end{align}
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 8.2 8.3 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ (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.
  11. ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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