Alpha Octantis

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Template:Short description

Alpha Octantis
Location of α Octantis (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 5.13[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type F4III + F5III[4]
U−B color index +0.13[5]
B−V color index +0.490±0.008[2]
Variable type EB[6]
Astrometry
Radial velocity (Rv)85.9±1.5[2] km/s
Proper motion (μ) RA: +22.5215[1] mas/yr
Dec.: −369.325[1] mas/yr
Parallax (π)22.5215±0.0955 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd 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
A
Mass1.9[8] M☉
Radius2.0[3] R☉
Luminosity7[3] L☉
Temperature6,700[3] K
Age1.1[8] Gyr
B
Mass2[3] M☉
Radius2.0[3] R☉
Luminosity7[3] L☉
Temperature6,700[3] K
Age1.1[8] Gyr
Other designations
Template:Odlist[9]
Database references
SIMBADdata

Alpha Octantis is a binary star[10] 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 also the faintest "alpha" star overall, with Alpha Mensae a close second.[11] 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.[2] The system is located approximately 148 light-years away from the Sun based on parallax.

File:AlphaOctLightCurve.png
A light curve for Alpha Octantis plotted from TESS data[12]

This is a double-lined spectroscopic binary star which consists of two similar main sequence stars, each with spectral type F,[3] 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 a debris disk; with a temperature of 219 K and is orbiting at a distance of 9.8 AU from its host star.[14]

References

Page Template:Reflist/styles.css has no content.

  1. ^ a b c d e Template:Cite DR2
  2. ^ a b c d Page Module:Citation/CS1/styles.css has no content.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. S2CID 119257644.
  3. ^ a b c d e f g h i Page Module:Citation/CS1/styles.css has no content."Alpha Octantis". stars.astro.illinois.edu. Retrieved 2025-07-13.
  4. ^ a b c The double-lined binary alpha Octantis, William Buscombe and Pamela M. Morris, The Observatory 80 (February 1960), pp. 28–29, Script error: No such module "CS1 identifiers"..
  5. ^ HR 8021, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 4, 2008.
  6. ^ a b Page Module:Citation/CS1/styles.css has no content.Samus', N. N; et al. (2017). "General catalogue of variable stars". Astronomy Reports. 5.1. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  7. ^ Page Module:Citation/CS1/styles.css has no content.Nordström, B.; et al. (2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs". Astronomy and Astrophysics. 418: 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. S2CID 11027621.
  8. ^ a b c Page Module:Citation/CS1/styles.css has no content.Asensio-Torres, R.; Janson, M.; Bonavita, M.; Desidera, S.; Thalmann, C.; Kuzuhara, M.; Henning, Th; Marzari, F.; Meyer, M. R.; Calissendorff, P.; Uyama, T. (2018-11-01). "SPOTS: The Search for Planets Orbiting Two Stars - III. Complete sample and statistical analysis". Astronomy & Astrophysics. 619: A43. arXiv:1807.08687. doi:10.1051/0004-6361/201833349. ISSN 0004-6361.
  9. ^ Page Module:Citation/CS1/styles.css has no content."* alf Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 4, 2008. {{cite web}}: Invalid |mode=Script error: No such module "Citation mode". (help)
  10. ^ Page Module:Citation/CS1/styles.css has no content.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. S2CID 14878976.
  11. ^ Page Module:Citation/CS1/styles.css has no content.Ridpath, Ian. "Star Tales – Octans". Retrieved 16 July 2025.
  12. ^ Page Module:Citation/CS1/styles.css has no content."MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  13. ^ Page Module:Citation/CS1/styles.css has no content.Makarov, Valeri V. (October 2003), "The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun", The Astronomical Journal, 126 (4): 1996–2008, Bibcode:2003AJ....126.1996M, doi:10.1086/378164.
  14. ^ Page Module:Citation/CS1/styles.css has no content.Trilling, D.E.; Stansberry, J.A.; Stapelfeldt, K.R.; Rieke, G.H.; Su, K.Y.L; Gray, R.O; Corbally, C.J; Bryden, G; Chen, C.H.; Boden, A; Beichman, C.A (2007). "DEBRIS DISKS IN MAIN-SEQUENCE BINARY SYSTEMS" (PDF). The Astrophysical Journal. 658 (2): 1289-1311. Bibcode:2007ApJ...658.1289T. doi:10.1086/511668.

Template:Stars of Octans

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