Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Octans |
Right ascension | 21h 04m 43.06347s[2] |
Declination | −77° 01′ 25.5735″[2] |
Apparent magnitude (V) | 5.13[3] |
Characteristics | |
Spectral type | F4III + F5III (spectroscopic binary)[4] |
U−B color index | +0.13[5] |
B−V color index | +0.490±0.008[3] |
Variable type | EB[6] |
Astrometry | |
Radial velocity (Rv) | 85.9±1.5[3] km/s |
Proper motion (μ) | RA: +22.5215[2] mas/yr Dec.: −369.325[2] mas/yr |
Parallax (π) | 22.5215 ± 0.0955 mas[2] |
Distance | 144.8 ± 0.6 ly (44.4 ± 0.2 pc) |
Absolute magnitude (MV) | 1.93±0.02[7] |
Orbit[4] | |
Period (P) | 9.073 d |
Eccentricity (e) | 0.39 |
Periastron epoch (T) | 2,435,302.404 |
Argument of periastron (ω) (secondary) | 276° |
Semi-amplitude (K1) (primary) | 47 km/s |
Semi-amplitude (K2) (secondary) | 47 km/s |
Details | |
Mass | 1.42[8] M☉ |
Radius | 3.69[9] R☉ |
Temperature | 6,270[7] K |
Metallicity [Fe/H] | 0.07[7] dex |
Rotational velocity (v sin i) | 85[10] km/s |
Age | 1.5±0.1[7] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Octantis is a binary star[12] system in the constellation of Octans. The name is Latinized from α Octantis. Despite being labeled the "alpha" star by Lacaille, it is not the brightest star in the constellation—that title belongs to Nu Octantis. It is visible to the naked eye as a faint, yellow-white-hued point of light with an overall apparent visual magnitude of approximately 5.13.[3] The system is located approximately 148 light-years away from the Sun based on parallax.
This is a double-lined spectroscopic binary star which consists of two similar giant stars, each with spectral type F, orbiting each other with a period of just over 9 days and an eccentricity of 0.39.[4] The pair form a Beta Lyrae-type eclipsing binary system, dropping by magnitude 0.04 during the primary eclipse.[6] This system is a bright X-ray source with a luminosity of 22.78×1029 ergs s−1.[13] The system displays an infrared excess suggesting the presence of two debris disks; the first has a temperature of 450 K and is orbiting at a distance of 1.40 AU from its host star, while the second is a much cooler 40 K and orbits 187.8 AU from the system.[9]