Beta Arae

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Beta Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
Cercle rouge 100%.svg

Location of β Arae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 17h 25m 17.98835s[1]
Declination −55° 31′ 47.5868″[1]
Apparent magnitude (V) 2.84[2]
Characteristics
Spectral type K3 Ib-IIa[3]
U−B color index +1.56[4]
B−V color index +1.46[4]
Astrometry
Radial velocity (Rv) -0.30 ± 0.20[3] km/s
Proper motion (μ) RA: −8.51[1] mas/yr
Dec.: −25.24[1] mas/yr
Parallax (π) 5.05 ± 0.64[1] mas
Distance approx. 650 ly
(approx. 200 pc)
Details
Mass 6.8 ± 0.4[5] M☉
Surface gravity (log g) 1.3[6] cgs
Temperature 4,582[6] K
Metallicity [Fe/H] +0.50[6] dex
Rotational velocity (v sin i) 5.4 ± 1.0[3] km/s
Age 50.1 ± 4.4[5] Myr
Other designations
CPD −55° 8100, FK5 645, HD 157244, HIP 85258, HR 6461, SAO 244725.[7]

Beta Arae (β Ara, β Arae) is the brightest star in the constellation Ara, with an apparent visual magnitude of 2.8.[2] Parallax measurements place it at a distance of roughly 650 light-years (200 parsecs) from Earth.[1]

The spectrum of this star matches a stellar classification of K3 Ib-IIa,[3] with the luminosity class notation 'Ib-IIa' indicating that the star lies part way between a higher luminosity bright giant (IIa) and a lower luminosity supergiant (Ib). This represents two of the evolutionary stages that a massive star passes through after it has exhausted the hydrogen at its core. Beta Arae is radiating energy from its outer envelope at an effective temperature of 4,582 K,[6] which causes it to take on the orange hue of a K-type star.[8] This enlarged star appears to be rotating slowly with a projected rotational velocity of about 5 km s−1.[3] The abundance of elements other than hydrogen and helium, what astronomer term the star's metallicity, is more than three times the abundance in the Sun.[3][9]

Rarely, this star is called by the name Vasat-ül-cemre in Turkish spelling, derived from Arabic word ﻭﺳﻂ (wasath) and ﺟﻤﻩﺮ (khamra), meaning "middle of fire".[10][unreliable source?] In Chinese, 杵 (Chǔ), meaning Pestle, refers to an asterism consisting of β Arae, σ Arae and α Arae.[11] Consequently, β Arae itself is known as 杵三 (Chǔ sān, English: the Third Star of Pestle.)[12]

References

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External links

  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 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 6.3 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ The abundance is estimated by taking [Fe/H] to the power of ten, thus:
    10[Fe/H] = 10+0.5 = 3.1
  10. ↑ (Turkish) YILDIZ ADLARI SÖZLÜĞÜ - Mustafa Pultar (Vasat-ül-cemre)
  11. ↑ (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.
  12. ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 1 日
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