Delta Arae

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Delta Arae
Ara constellation map.png
δ Arae (lower center) in the Ara Constellation
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ara
Right ascension 17h 31m 05.91272s[1]
Declination –60° 41′ 01.8522″[1]
Apparent magnitude (V) 3.62[2]
Characteristics
Spectral type B8 Vn[3] + G8 V[4]
U−B color index –0.31[2]
B−V color index –0.10[2]
Astrometry
Radial velocity (Rv) +10[5] km/s
Proper motion (μ) RA: –54.01[1] mas/yr
Dec.: –99.25[1] mas/yr
Parallax (π) 16.48 ± 0.34[1] mas
Distance 198 ± 4 ly
(61 ± 1 pc)
Details
Mass 3.56[6] M☉
Radius 3.12 ± 0.15[7] R☉
Surface gravity (log g) 3.81 ± 0.06[7] cgs
Temperature 11,962 ± 86[7] K
Rotational velocity (v sin i) 255[4] km/s
Age 125[8] Myr
Other designations
CPD –60° 6842, FK5 648, HD 158094, HIP 85727, HR 6500, SAO 253945.[9]

Delta Arae (δ Arae, δ Ara) is the Bayer designation for a double star in the southern constellation Ara. It has an apparent visual magnitude of 3.62[2] and is visible to the naked eye. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61 parsecs) distant from the Earth.[1]

Delta Arae is massive B-type main sequence star with a stellar classification of B8 Vn.[3] The 'n' suffix indicates the absorption lines are spread out broadly because the star is spinning rapidly. It has a projected rotational velocity of 255 km/s, resulting in an equatorial bulge with a radius 13% larger than the polar radius.[4] It has a magnitude 9.5 companion G-type main sequence star that may form a binary star system with Delta Arae.[6]

There is a 12th magnitude optical companion located 47.4 arcseconds away along a position angle of 313°.[8]

Etymology

Delta Arae was known as 龜三 (meaning: "the 3rd (star) of Guī") in traditional Chinese astronomy.[10][11]

Allen erroneously called it with ζ Arae as Tseen Yin (天陰).[12] He probably confused constellation "Ara" with "Ari". Tseen Yin was lain[clarification needed] in Aries.[10][11]

See also

References

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Further reading

  • 大崎正次 (1987): 「中国の星座・星名の同定一覧表」『中国の星座の歴史』 雄山閣出版, pp. 312, 328.(Japanese)

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 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. ↑ 4.0 4.1 4.2 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.
  7. ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found. Cite error: Invalid <ref> tag; name "aaa523_A73" defined multiple times with different content
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 Chevalier, S., and Tsuchihashi, P., (1911): "Catalogue d'Étoiles fixes, observés a Pekin sous l'Empereur Kien Long (Qianlong (Chien-Lung)), XVIIIe siecle", Annales de l'Observatoire Astronomique de Zô-Sé.
  11. ↑ 11.0 11.1 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(Chinese)
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.[1]
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