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Beta Octantis, Latinized from β Octantis, is a probable astrometric binary[10] star system in the southern circumpolar constellation of Octans. It is faintly visible to the naked eye with an apparent visual magnitude of 4.13.[2] Based upon an annual parallax shift of 21.85 mas as seen from Earth, it is located about 149 light years from the Sun. It is moving away from the Sun with a radial velocity of +19 km/s.[5]

β Octantis
Octans constellation map.svg
Red circle.svg
Location of β Octantis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Octans
Right ascension  22h 46m 03.51098s[1]
Declination −81° 22′ 53.8120″[1]
Apparent magnitude (V) 4.13[2]
Spectral type A9IV-V[3]
U−B color index +0.11[4]
B−V color index +0.20[4]
Radial velocity (Rv)+19.0±0.6[5] km/s
Proper motion (μ) RA: −54.49[1] mas/yr
Dec.: +1.16[1] mas/yr
Parallax (π)21.85 ± 0.43[1] mas
Distance149 ± 3 ly
(45.8 ± 0.9 pc)
Absolute magnitude (MV)+0.83[2]
Mass2.27[6] M
Radius3.2[7] R
Luminosity42[6] L
Surface gravity (log g)4.15[8] cgs
Temperature8,006[8] K
Metallicity [Fe/H]−0.02[9] dex
Rotational velocity (v sin i)49[6] km/s
Age496[8] Myr
Other designations
β Oct, CPD−82° 889, FK5 924, GC 31712, HD 214846, HIP 112405, HR 8630, SAO 258941
Database references

Based upon a stellar classification of A9IV-V,[3] the visible component is an evolving, white-hued A-type star with a spectrum that shows mixed traits of a main sequence and a subgiant star. It has an estimated 2.27[6] times the mass of the Sun and 3.2[7] times the Sun's radius. The star is around 500 million years old[8] with a projected rotational velocity of 49 km/s.[6] It is radiating 42[6] times the Sun's luminosity from its photosphere at an effective temperature of 8,006 K.[8]


  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. Vizier catalog entry
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  5. ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. ^ a b c d e f Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. Vizier catalog entry
  7. ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
  8. ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. Vizier catalog entry
  9. ^ Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. Vizier catalog entry
  10. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.