Epsilon1 Arae

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Epsilon1 Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
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The location of ε1 Arae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ara
Right ascension 16h 59m 35.04880s[1]
Declination –53° 09′ 37.5713″[1]
Apparent magnitude (V) +4.068[2]
Characteristics
Spectral type K3 III[3]
U−B color index +1.71[4]
B−V color index +1.45[4]
Astrometry
Radial velocity (Rv) +23.1[5] km/s
Proper motion (μ) RA: +2.16[1] mas/yr
Dec.: +22.04[1] mas/yr
Parallax (π) 9.04 ± 0.27[1] mas
Distance 360 ± 10 ly
(111 ± 3 pc)
Absolute magnitude (MV) –0.79 ± 0.16
Details
Mass 1.74 ± 0.24[6] M
Radius 33.7 ± 3.4[6] R
Surface gravity (log g) 1.80[2] cgs
Temperature 4,176[2] K
Metallicity [Fe/H] 0.08 ± 0.05[2] dex
Age 1.70 ± 0.57[6] Gyr
Other designations
CP –52° 10372, FK5 632, HD 152980, HIP 83153, HR 6295, SAO 244331.[7]

Epsilon1 Arae1 Ara, ε1 Arae) is the Bayer designation for a star in the constellation Ara, the Altar. It is visible to the naked eye with an apparent visual magnitude of +4.1[2] Based upon an annual parallax shift of 9.04 mas,[1] this star is around 360 light-years (110 parsecs) distant from the Earth.

ε1 Arae is an evolved giant star[6] with a stellar classification of K3 III.[3] It is around 74% more massive than the Sun. At an age of about 1.7 billion years, the outer envelope of the star has expanded to almost 34 times the Sun's radius.[6] It is radiating energy into space at an effective temperature of 4,176 K,[2] giving it the orange-hued glow of a K-type star.[8]

ε1 Arae was known as 龜一 (meaning: "the 1st (star) of Guī") in traditional Chinese astronomy.[9][10] Allen erroneously called it as Tso Kang (左更).[11] He probably confused constellation "Ara" with "Ari". Tso Kang was lain[clarification needed] in Aries.[9][10]

References

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  9. 9.0 9.1 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.
  10. 10.0 10.1 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(Chinese)
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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, 326.(Japanese)

External links