{{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 | equinox = J2000.0 (ICRS) | constell = 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<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 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<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 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 Octantis''' is a binary star<ref name=Eggleton2008/> 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.<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 of approximately 5.13.<ref name=Anderson2012/> The system is located approximately 148 light-years away from the Sun based on parallax.
[[File:AlphaOctLightCurve.png|thumb|left|250px|A light curve for Alpha Octantis plotted from ''TESS'' data<ref name=MAST/>]] This is a double-lined spectroscopic binary star which consists of two similar main sequence stars, each with spectral type F,<ref name=kaler/> orbiting each other with a period of just over 9 days and an eccentricity of 0.39.<ref name=obs/> The pair form a Beta Lyrae-type eclipsing binary system, dropping by magnitude 0.04 during the primary eclipse.<ref name=Samus2017/> This system is a bright X-ray source with a luminosity of {{Val|22.78e29|u=ergs s<sup>−1</sup>}}.<ref name=Makarov2003/> The system displays an infrared excess suggesting the presence of a 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 | 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