Sigma Octantis

Sigma Octantis
Location of σ Octantis (circled)
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]
Distance294 ± 2 ly
(90.1 ± 0.5 pc)
Absolute magnitude (MV)0.86±0.09[6]
Details
Mass1.59[7] M☉
Radius4.4[1] R☉
Luminosity44[1] L☉
Surface gravity (log g)3.71[7] cgs
Temperature7,415±252[7] K
Metallicity [Fe/H]−0.5[1] dex
Rotational velocity (v sin i)145[4] km/s
Age912[7] Myr
Other designations
Polaris Australis, σ Oct, CPD−89°47, FK5 923, HD 177482, HIP 104382, HR 7228, SAO 258857[8]
Database references
SIMBADdata

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.

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.

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  2. ^ a b c Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference houk1975 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Rodriguez2000 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Antonello1997 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference David2015 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).