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.
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] |
Distance | 360 ± 10 ly (111 ± 3 pc) |
Absolute magnitude (MV) | –0.79 ± 0.16[6] |
Details | |
Mass | 1.74 ± 0.24[7] M☉ |
Radius | 33.7 ± 3.4[7] 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[7] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
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]
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