Eta Arae
 The location of η Arae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ara |
| Right ascension | 16h 49m 47.15653s |
| Declination | –59° 02′ 28.9575″ |
| Apparent magnitude (V) | 3.76 |
| Characteristics | |
| Spectral type | K5 III |
| U−B color index | +1.93 |
| B−V color index | +1.57 |
| Astrometry | |
| Radial velocity (Rv) | +9.0 km/s |
| Proper motion (μ) |
RA: +39.73 mas/yr Dec.: –24.91 mas/yr |
| Parallax (π) | 10.90 ± 0.20mas |
| Distance | 299 ± 5 ly (92 ± 2 pc) |
| Absolute magnitude (MV) | –1.14 ± 0.14 |
| Details | |
| Mass | 1.02 ± 0.12 M☉ |
| Radius | 55.9 ± 7.3 R☉ |
| Surface gravity (log g) | 0.92 ± 0.12 cgs |
| Temperature | 3,886 K |
| Metallicity [Fe/H] | –0.37 dex |
| Age | 7.11 ± 2.34 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Arae (η Ara, η Arae) is the Bayer designation for a single star in the southern constellation of Ara. It is approximately 299 light-years (92 parsecs) from Earth and is visible to the naked eye with an apparent visual magnitude of 3.76.
The spectrum of this star matches a stellar classification of K5 III, indicating that, at an estimated age of seven billion years, it has reached the giant star stage of its evolution. With a mass nearly the same as the Sun, it has an outer envelope that has expanded to nearly 56 times the Sun's radius. The star is now spinning so slowly that it takes more than eleven years to complete a single rotation. Eta Arae is radiating energy into space at an effective temperature of 3,886 K, giving it the orange-hued glow of a K-type star.
It has a 14th magnitude optical companion, located 25.7 arcseconds away.
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