Epsilon1 Arae

For other star systems with this Bayer designation, see Epsilon Arae.
Epsilon1 Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
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 mas[1]
Distance360 ± 10 ly
(111 ± 3 pc)
Absolute magnitude (MV)–0.79 ± 0.16[6]
Details
Mass1.74 ± 0.24[7] M☉
Radius33.7 ± 3.4[7] R☉
Surface gravity (log g)1.80[2] cgs
Temperature4,176[2] K
Metallicity [Fe/H]0.08 ± 0.05[2] dex
Age1.70 ± 0.57[7] Gyr
Other designations
CPD–52° 10372, FK5 632, HD 152980, HIP 83153, HR 6295, SAO 244331.[8]
Database references
SIMBADdata

Epsilon1 Arae (ε1 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[7] 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.[7] 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.[9]

ε1 Arae was known as 龜一(spelled as "Guī yī", meaning: "the 1st (star) of Guī") in traditional Chinese astronomy.[10][11] Allen erroneously called it Tso Kang (左更).[12] He probably confused the constellation "Ara" with "Ari", as Tso Kang is actually in Aries.[10][11]

  1. ^ a b c d e f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference aaa515_A11 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference clpl4_99 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference scfs was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Setaiwan2004 was invoked but never defined (see the help page).
  7. ^ a b c d e Cite error: The named reference aaa458_2_609 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  10. ^ a b 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. ^ a b 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(in Chinese)
  12. ^ Cite error: The named reference allen was invoked but never defined (see the help page).