# Alpha Octantis

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Alpha_Octantis
> Markdown URL: https://mediated.wiki/source/Alpha_Octantis.md
> Source: https://en.wikipedia.org/wiki/Alpha_Octantis
> Source revision: 1328936663
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Binary star system in the constellation Octans}}
{{Starbox begin}}
{{Starbox image
| image =
{{Location mark
|image=Octans constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=α Octantis
|x=620|y=332
}}
| caption = Location of α Octantis (circled in red)
}}
{{Starbox observe
 | epoch = [J2000.0](/source/J2000.0)
 | equinox = [J2000.0](/source/J2000.0) ([ICRS](/source/International_Celestial_Reference_System))
 | constell = [Octans](/source/Octans)
 | ra = {{RA|21|04|43.06347}}<ref name=GaiaDR2>{{cite DR2|5330765974462198784}}</ref>
 | dec = {{DEC|−77|01|25.5735}}<ref name=GaiaDR2/>
 | appmag_v=5.13<ref name=Anderson2012/>
}}
{{Starbox character
 | type = [Main sequence](/source/Main_sequence)<ref name=kaler/>
 | class = F4III + F5III<ref name=obs>The double-lined binary alpha Octantis, William Buscombe and Pamela M. Morris, ''The Observatory'' '''80''' (February 1960), pp. 28–29, {{Bibcode|1960Obs....80...28B}}.</ref>
 | u-b = +0.13<ref name=bsc1>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=8021 HR 8021], database entry, The Bright Star Catalogue,  5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., [CDS](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg) ID [http://vizier.u-strasbg.fr/viz-bin/Cat?V/50 V/50].  Accessed on line September 4, 2008.</ref>
 | b-v = {{Val|+0.490|0.008}}<ref name=Anderson2012/>
 | variable = [EB](/source/Beta_Lyrae_variable)<ref name=Samus2017>{{cite journal | title=General catalogue of variable stars | version=5.1 | last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V | last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N | last5=Pastukhova | first5=E. N | journal=Astronomy Reports | display-authors=1 | volume=61 | issue=1 | pages=80 | year=2017 | doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}</ref>
}}
{{Starbox astrometry
 | radial_v = {{Val|85.9|1.5}}<ref name=Anderson2012/>
 | prop_mo_ra = +22.5215<ref name=GaiaDR2/>
 | prop_mo_dec = −369.325<ref name=GaiaDR2/>
 | parallax = 22.5215
 | p_error = 0.0955
 | parallax_footnote = <ref name=GaiaDR2/>
 | absmag_v= {{Val|1.93|0.02}}<ref name=Geneva>{{cite journal|title=The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs|author1=Nordström, B.|display-authors=etal|journal=Astronomy and Astrophysics|volume=418|pages=989–1019|date=2004|bibcode=2004A&A...418..989N|doi=10.1051/0004-6361:20035959|arxiv=astro-ph/0405198|s2cid=11027621}}</ref>
}}
{{Starbox orbit
 | reference=<ref name=obs/>
 | period_unitless=9.073 d
 | k1=47
 | k2=47
 | periastron=2,435,302.404
 | eccentricity=0.39
 | periarg=276
}}
{{Starbox detail
 | source =  
 | component1 = A
 | mass = 1.9<ref name=SPOTS/>
 | radius = 2.0<ref name=kaler/>
 | luminosity = 7<ref name=kaler/>
 | temperature = 6,700<ref name=kaler/>
 | age_gyr = 1.1<ref name=SPOTS/>
 | component2 = B
 | mass2 = 2<ref name=kaler/>
 | radius2 = 2.0<ref name=kaler/>
 | luminosity2 = 7<ref name=kaler/>
 | temperature2 = 6,700<ref name=kaler/>
 | age_gyr2 = 1.1<ref name=SPOTS/>
}}
{{Starbox catalog
 | names={{odlist | B=α&nbsp;Oct | CD=−77°1053 | CPD=−77°1474 | FK5=787 | HD=199532 | HIP=104043 | HR=8021 | SAO=257879 | GC=29343 | LTT=8327 | NLTT=50332 | PPM=374864 }}<ref name=sb0>{{cite simbad|title=* alf Oct|access-date=September 4, 2008}}</ref>
}}
{{Starbox reference
 | Simbad=alf+Oct
}}
{{Starbox end}}

'''Alpha&nbsp;Octantis''' is a [binary star](/source/binary_star)<ref name=Eggleton2008/> system in the [constellation](/source/constellation) of [Octans](/source/Octans). The name is [Latinized](/source/Romanization_of_Greek) from α&nbsp;Octantis. Despite being labeled the "alpha" star by [Lacaille](/source/Nicolas-Louis_de_Lacaille), it is not the brightest star in the constellation—that title belongs to [Nu Octantis](/source/Nu_Octantis). It is also the faintest "alpha" star overall, with [Alpha Mensae](/source/Alpha_Mensae) a close second.<ref name=Ridpath/> It is visible to the naked eye as a faint, yellow-white-hued point of light with an overall [apparent visual magnitude](/source/apparent_visual_magnitude) of approximately 5.13.<ref name=Anderson2012/> The system is located approximately 148&nbsp;[light-year](/source/light-year)s away from the [Sun](/source/Sun) based on [parallax](/source/stellar_parallax).

[[File:AlphaOctLightCurve.png|thumb|left|250px|A [light curve](/source/light_curve) for Alpha Octantis plotted from ''[TESS](/source/Transiting_Exoplanet_Survey_Satellite)'' data<ref name=MAST/>]]
This is a double-lined [spectroscopic binary](/source/spectroscopic_binary) star which consists of two similar [main sequence](/source/main_sequence) stars, each with [spectral type](/source/spectral_type) F,<ref name=kaler/> orbiting each other with a [period](/source/orbital_period) of just over 9 days and an [eccentricity](/source/orbital_eccentricity) of 0.39.<ref name=obs/> The pair form a [Beta Lyrae-type](/source/Beta_Lyrae_variable) [eclipsing binary](/source/eclipsing_binary) system, dropping by magnitude 0.04 during the primary eclipse.<ref name=Samus2017/> This system is a bright [X-ray source](/source/X-ray_astronomy) with a luminosity of {{Val|22.78e29|u=ergs s<sup>−1</sup>}}.<ref name=Makarov2003/> The system displays an [infrared excess](/source/infrared_excess) suggesting the presence of a [debris disk](/source/debris_disk); with a temperature of {{Val|219|ul=K}} and is orbiting at a distance of {{Val|9.8|ul=AU}} from its host star.<ref>{{Cite journal |last1=Trilling |first1=D.E. |last2=Stansberry |first2=J.A. |last3=Stapelfeldt |first3=K.R. |last4=Rieke |first4=G.H. |last5=Su |first5=K.Y.L |last6=Gray |first6=R.O |last7=Corbally |first7=C.J |last8=Bryden |first8=G |last9=Chen |first9=C.H. |last10=Boden |first10=A |last11=Beichman |first11=C.A |year=2007 |title=DEBRIS DISKS IN MAIN-SEQUENCE BINARY SYSTEMS |url=https://w.astro.berkeley.edu/~kalas/disksite/library/trilling07a.pdf |journal=The Astrophysical Journal |volume=658 |issue=2 |page=1289-1311|doi=10.1086/511668 |bibcode=2007ApJ...658.1289T }}</ref>

{{clear left}}
==References==
{{Reflist|refs=

<ref name=MAST>{{cite web
 | title=MAST: Barbara A. Mikulski Archive for Space Telescopes
 | url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html
 | publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>

<ref name=Makarov2003>{{citation
 | last1=Makarov | first1=Valeri V.
 | title=The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun
 | journal=The Astronomical Journal | postscript=.
 | volume=126 | issue=4 | pages=1996–2008 | date=October 2003
 | doi=10.1086/378164 | bibcode=2003AJ....126.1996M | doi-access=free }}</ref>

<ref name=Eggleton2008>{{cite journal
 | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
 | title=A catalogue of multiplicity among bright stellar systems
 | journal=[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)
 | volume=389 | issue=2 | pages=869–879 | date=September 2008
 | bibcode=2008MNRAS.389..869E | arxiv=0806.2878
 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | s2cid=14878976 }}</ref>

<ref name=SPOTS>{{Cite journal |last=Asensio-Torres |first=R. |last2=Janson |first2=M. |last3=Bonavita |first3=M. |last4=Desidera |first4=S. |last5=Thalmann |first5=C. |last6=Kuzuhara |first6=M. |last7=Henning |first7=Th |last8=Marzari |first8=F. |last9=Meyer |first9=M. R. |last10=Calissendorff |first10=P. |last11=Uyama |first11=T. |date=2018-11-01 |title=SPOTS: The Search for Planets Orbiting Two Stars - III. Complete sample and statistical analysis |journal=Astronomy & Astrophysics |language=en |volume=619 |pages=A43 |doi=10.1051/0004-6361/201833349 |issn=0004-6361|arxiv=1807.08687 }}</ref>

<ref name=Anderson2012>{{cite journal
 | title=XHIP: An extended hipparcos compilation
 | last1=Anderson | first1=E. | last2=Francis | first2=Ch.
 | journal=Astronomy Letters | arxiv=1108.4971
 | volume=38 | issue=5 | pages=331 | year=2012
 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | s2cid=119257644 }}</ref>

<ref name=kaler>{{Cite web |title=Alpha Octantis |url=http://stars.astro.illinois.edu/sow/alphaoct.html |access-date=2025-07-13 |website=stars.astro.illinois.edu}}</ref>

<ref name=Ridpath>{{cite web |last=Ridpath |first=Ian |author-link=Ian Ridpath |title=Star Tales – Octans |url=http://www.ianridpath.com/startales/octans.html |access-date=16 July 2025}}</ref>

}}

{{Stars of Octans}}
<!-- Properties -->

{{DEFAULTSORT:Alpha Octantis}}
Category:F-type giants
Category:Spectroscopic binaries
Category:Circumstellar disks
Category:Beta Lyrae variables
<!-- Identifiers -->
Category:Octans
Octantis, Alpha
CD-77 01053
199532
104043
8021

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Adapted from the Wikipedia article [Alpha Octantis](https://en.wikipedia.org/wiki/Alpha_Octantis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Alpha_Octantis?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.