Nu Octantis
ν Octantis, Latinised as Nu Octantis, is the brightest star in the constellation of Octans. It is a spectroscopic binary star with a period around 2.9 years. Its apparent magnitude is 3.73. Located around 21.20 parsecs (69.1 ly) distant, the primary is an orange giant of spectral type K1III, a star that has used up its core hydrogen and has expanded. The secondary star is likely either a red dwarf or a white dwarf, from its relatively low mass.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans |
| Right ascension | 21h 41m 28.64977s |
| Declination | −77° 23′ 24.1563″ |
| Apparent magnitude (V) | 3.73 |
| Characteristics | |
| Spectral type | K1III |
| U−B color index | +0.89 |
| B−V color index | +1.00 |
| Astrometry | |
| Radial velocity (Rv) | +34.40 km/s |
| Proper motion (μ) | RA: +66.41 mas/yr Dec.: −239.10 mas/yr |
| Parallax (π) | 51.5172 ± 0.6525 mas |
| Distance | 63.3 ± 0.8 ly (19.4 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.10 +2.02 |
| Orbit | |
| Period (P) | 1050.69+0.05 −0.07 d |
| Semi-major axis (a) | 2.62959+0.00009 −0.00011 AU |
| Eccentricity (e) | 0.23680±0.00007 |
| Inclination (i) | 70.8±0.9° |
| Longitude of the node (Ω) | 87±1.2° |
| Argument of periastron (ω) (secondary) | 74.970±0.016° |
| Semi-amplitude (K1) (primary) | 7.032±0.003 km/s |
| Details | |
| Nu Octantis A | |
| Mass | 1.04 1.61 M☉ |
| Radius | 5.9 5.81±0.12 R☉ |
| Luminosity | 17.53 L☉ |
| Surface gravity (log g) | 3.12±0.10 cgs |
| Temperature | 4,860±40 K |
| Metallicity [Fe/H] | +0.18±0.04 dex |
| Rotational velocity (v sin i) | 2.0 km/s |
| Age | ~2.5-3 Gyr |
| Nu Octantis B | |
| Mass | 0.585 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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