Nu Octantis
 Location of ν Octantis (circled) |
|
| 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) | 45.25 ± 0.25mas |
| Distance | 72.1 ± 0.4 ly (22.1 ± 0.1 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 | |
| Mass | 1.04 1.61 / 0.585 M☉ |
| Radius | 5.9 5.81 ± 0.12 R☉ |
| Luminosity | 17.53 L☉ |
| Surface gravity (log g) | 3.12 ± 0.10 cgs |
| Temperature | 4860 ± 40 K |
| Metallicity [Fe/H] | +0.18 ± 0.04 dex |
| Rotational velocity (v sin i) | 2.0 km/s |
| Age | ~2.5-3 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Nu Octantis is a spectroscopic binarystar in the constellation Octans 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 a red dwarf from its low mass.
In 2009, the system was hypothesized to contain an exoplanet based on perturbations in the orbital period. A prograde solution was quickly ruled out but a retrograde solution remains a possibility, although the variations may instead be due to the secondary star being itself a close binary, since the formation of a planet in such a system would difficult due to dynamic perturbations.
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