Epsilon2 Arae
Star in the constellation Ara
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Epsilon2 Arae is a double star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from ε2 Arae, and abbreviated Epsilon2 Ara or ε2 Ara. Based on parallax measurements, it is 89 light-years (27 parsecs) distant from Earth. With a combined apparent visual magnitude of 5.27,[2] this system is faintly visible to the naked eye as a point of light.
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h 03m 08.754s[1] |
| Declination | −53° 14′ 12.97″[1] |
| Apparent magnitude (V) | 5.270[2] (5.44 + 8.65)[3] |
| Characteristics | |
| Spectral type | F5 V Fe+0.5[4] + DA3.2[5] |
| U−B color index | +0.015[6] |
| B−V color index | +0.498±0.005[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.9[7] km/s |
| Proper motion (μ) | RA: −22.409 mas/yr[1] Dec.: −143.793 mas/yr[1] |
| Parallax (π) | 37.3696±0.1347 mas[1] |
| Distance | 87.3 ± 0.3 ly (26.76 ± 0.10 pc) |
| Absolute magnitude (MV) | 3.27[8] |
| Orbit[9] | |
| Primary | ε2 Ara Aa |
| Name | ε2 Ara Ab |
| Period (P) | 41.3 yr |
| Semi-major axis (a) | 0.589″ |
| Eccentricity (e) | 0.622 |
| Inclination (i) | 133.8° |
| Longitude of the node (Ω) | 73.6° |
| Details | |
| ε2 Ara Aa | |
| Mass | 1.40+0.01 −0.02[10] M☉ |
| Radius | 1.8[2] R☉ |
| Luminosity | 4.56[2] L☉ |
| Surface gravity (log g) | 4.29[8] cgs |
| Temperature | 6,577[8] K |
| Metallicity [Fe/H] | +0.02[8] dex |
| Rotational velocity (v sin i) | 45.4[11] km/s |
| Age | 1.77+0.29 −0.26[10] Gyr |
| ε2 Ara C | |
| Mass | 0.66±0.07[12] M☉ |
| Radius | 0.0124±0.0003[12] R☉ |
| Surface gravity (log g) | 8.07±0.04[12] cgs |
| Temperature | 15,507±230[12] K |
| Other designations | |
| CPD−53°8316, GC 22956, GJ 3985, HD 153580, HIP 83431, HR 6314, SAO 244388, PPM 345633, WDS J17031-5314A[6] | |
| Database references | |
| SIMBAD | data |
The brighter star is a magnitude 5.44 F-type main sequence star with a stellar classification of F5 V Fe+0.5.[4] The Fe+0.5 notation indicates that it has a somewhat higher than normal abundance of iron. It has an estimated age of 1.8[10] billion years and a relatively high rate of rotation with a projected rotational velocity of 45 km/s.[11] This star has 1.4[10] times the mass of the Sun and 1.8 times the Sun's radius.[2] It is radiating 4.56[2] times the luminosity of the Sun from its photosphere at an effective temperature of 6,577 K.[8] The metallicity of the star, a measure of the abundance of more massive elements, is similar to the Sun.[8] It is a candidate pulsating star.[13]
There is a magnitude 8.65 stellar companion, component Ab, at an angular separation of 0.590 arcseconds.[3] The pair have an estimated orbital period of 41.3 years.[9] A common proper motion white dwarf companion, WD 1659-53, lies at an angular separation of 113.76″. Designated component C, it is magnitude 13.47 with a classification of DA3.2.[14][5]