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Sigma Octantis
Star in the constellation Octans / From Wikipedia, the free encyclopedia
Sigma Octantis is a solitary[9] star in the Octans constellation that forms the pole star of the Southern Hemisphere. Its name is also written as σ Octantis, abbreviated as Sigma Oct or σ Oct, and it is officially named Polaris Australis (/poʊˈlɛərɪs ɔːˈstreɪlɪs/).[10] The star is positioned one degree away from the southern celestial pole of the Southern Hemisphere, lying in nearly opposite direction to the North Star on the celestial sphere.
Quick Facts Constellation, Right ascension ...
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Octans |
Right ascension | 21h 08m 46.86357s[1] |
Declination | −88° 57′ 23.3983″[1] |
Apparent magnitude (V) | 5.47[2] |
Characteristics | |
Spectral type | F0 IV[3] |
U−B color index | +0.13[2] |
B−V color index | +0.26[2] |
Variable type | δ Sct[4] |
Astrometry | |
Radial velocity (Rv) | +11.9[5] km/s |
Proper motion (μ) | RA: +26.323[1] mas/yr Dec.: +4.721[1] mas/yr |
Parallax (π) | 11.1005 ± 0.0616 mas[1] |
Distance | 294 ± 2 ly (90.1 ± 0.5 pc) |
Absolute magnitude (MV) | 0.86±0.09[6] |
Details | |
Mass | 1.59[7] M☉ |
Radius | 4.4[1] R☉ |
Luminosity | 44[1] L☉ |
Surface gravity (log g) | 3.71[7] cgs |
Temperature | 7,415±252[7] K |
Metallicity [Fe/H] | −0.5[1] dex |
Rotational velocity (v sin i) | 145[4] km/s |
Age | 912[7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Close
Located approximately 294 light-years from Earth, it is classified as a subgiant with a spectral type of F0 IV. Sigma Octantis has an apparent magnitude of 5.5, but is slightly variable and is classified as a Delta Scuti variable.