{{Short description|Star in the constellation Centaurus}} {{Starbox begin | name=RR Centauri }} {{Starbox image | image = [[File:RR_Cen_Eclipse_Phase.png|250px]] | caption = Light curve of RR Cen. }} {{Starbox observe | epoch = J2000 | ra = {{RA|14|16|57.22}}<ref name=SIMBAD/> | dec = {{DEC|-57|51|15.6}}<ref name=SIMBAD/> | appmag_v = 7.27 - 7.68<ref name=gcvs/> | constell = [[Centaurus]] }} {{Starbox character | class = F0 V<ref name=eker/> | b-v = +0.36<ref name=Loden/> | u-b = +0.05<ref name=Loden/> | variable = [[W Ursae Majoris variable|W Uma]]<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref> }} {{Starbox astrometry | radial_v = -16.0 <ref name=kinematics/> | prop_mo_ra = -52.00<ref name=aaa474_2_653/> | prop_mo_dec = -22.63<ref name=aaa474_2_653/> | parallax = 10.16 | p_error = 0.61 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = +1.882<ref name=eker>{{cite journal|bibcode=2009AN....330...68E|arxiv=0807.4989|title=New absolute magnitude calibrations for W Ursa Majoris type binaries|journal=Astronomische Nachrichten|volume=330|pages=68–76|last1=Eker|first1=Z.|last2=Bilir|first2=S.|last3=Yaz|first3=E.|last4=Demircan|first4=O.|last5=Helvaci|first5=M.|year=2009|issue=1|doi=10.1002/asna.200811041|s2cid=15071352}}</ref> }} {{Starbox orbit | reference = <ref name = PASJ/> | primary = RR Cen A | name = RR Cen B | period = | period_unitless = 0.60569 days | axis = | axis_unitless = {{solar radius|3.92 ± 0.19}} | eccentricity = 0 | inclination = 81.00 ± 0.44 | node = | periastron = | periarg = | periarg_primary = | k1 = | k2 = }} {{Starbox detail | source=<ref name = PASJ/> | component1 = RR Cen A | mass = {{nowrap|1.82 ± 0.26}} | radius = {{nowrap|2.1 ± 0.01}} | luminosity = 8.89 | temperature = 6,912 | component2 = RR Cen B | mass2 = {{nowrap|0.38 ± 0.06}} | radius2 = {{nowrap|1.05 ± 0.03}} | luminosity2 = 2.2 | temperature2 = {{nowrap|6,891 ± 13}} }} {{Starbox catalog | names=[[Variable star designation|RR]] Cen, [[2MASS]] J14165721-5751156, [[Henry Draper Catalogue|HD]] 124689, [[Hipparcos catalogue|HIP]] 69779, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 241587, [[Tycho-2 Catalogue|TYC]] 8686-210-1, [[Cordoba Durchmusterung]] CD-57 5498<ref name=SIMBAD/> }} {{Starbox reference | Simbad=HD+124689 }} {{Starbox end}}
'''RR Centauri''' is a [[variable star]] with an [[apparent magnitude]] of +7.3 when it is at its brightest. It is located in the constellation of [[Centaurus]], approximately 320 light years distant from the [[Solar System]].<ref name=aaa474_2_653/>
The system is a contact binary of the [[W Uma star|W UMa type]] - two stars in physical contact whose two components share a gaseous envelope — with a variation in brightness of 0.41 magnitude.<ref name=PASJ/> Its spectral type is A9V or F0V.<ref name=SIMBAD/> The binary nature of the star was discovered in 1896 by the Scottish-South African astronomer [[Alexander William Roberts|Alexander Roberts]], so the system has been well observed for over a century.<ref name=Roberts/> The primary component has a mass of 1.82 solar masses, an effective temperature of around 6900 K, and a radius somewhat larger than twice the solar radius.<ref name=PASJ/> The secondary component is 0.39 solar masses, giving a mass ratio of the system (''q'') of 0.210. the secondary has a temperature of about 6890 K and a radius is almost equal to the solar radius.
The orbital period of this system is {{convert|0.6057|d|h}}. Calculations by astronomers from the Chinese Academy of Sciences show a possible cyclic variation in orbital period over {{val|65.1|0.4|u=years}} whose amplitude is {{val|0.0124|0.0007|u=days}}.<ref name=PASJ/> The origin of this periodic variation could be due to the gravitational influence of a third object yet observed. Superimposed on this variation seems to be a secular increase in the period of {{val|1.21e-7|u=d/yr}}, suggesting that there is transfer of stellar mass from secondary to primary component. If this increase is confirmed, RR Centauri may evolve into a single rapidly rotating star.{{Citation needed|date=July 2025}}
==References== <references> <ref name=SIMBAD>{{cite web | title=V* RR Cen -- Eclipsing binary of W UMa type (contact binary) | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=RR+Cen&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id | access-date=2016-02-27 }}</ref> <ref name = Roberts>{{Cite journal | last1=Roberts | first1=Alexander | year = 1903 | title = Determination of the Orbital Elements of RR Centauri from the Observed Light Curve | journal = Monthly Notices of the Royal Astronomical Society | volume = 63 | issue = 8 | pages = 540–549| bibcode=1903MNRAS..63..536R| doi= 10.1093/mnras/63.8.527| doi-access = free }}</ref> <ref name=Loden>{{Cite journal | first1=L.O. | last1=Loden | title=Continued studies of loose clusterings in the Southern Milky Way | journal=Astronomy and Astrophysics Supplement | volume=38 | pages=355 | year=1979 | bibcode=1979A&AS...38..355L}}</ref> <ref name=kinematics>{{Cite journal | first1=S | last1=Bilir | first2=Y | last2=Karatas | first3=O | last3=Demircan | first4=Z | last4=Eker | title=Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation | journal=Monthly Notices of the Royal Astronomical Society | volume=357 | issue=2 | pages=497–517 | year= 2005 | bibcode=2005MNRAS.357..497B| doi=10.1111/j.1365-2966.2005.08609.x | doi-access=free |arxiv = astro-ph/0411291 | s2cid=16274339 }}</ref> <ref name=aaa474_2_653>{{cite journal | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref> <ref name = PASJ>{{cite journal | last1 = Yuan-Gui | first1 = Y. | last2 = Sheng-Bang | first2 = Q. | last3 = Li-Ying | first3 = Z. | last4 = Jia-Jia | first4 = H. | last5 = Jin-Zhao| first5 = Y | year = 2005 | title= Photometric Investigations of Three Short-Period Binary Systems: GSC 0763–0572, RR Centauri, and Epsilon Coronae Australis | journal = Publications of the Astronomical Society of Japan | volume = 57 | issue = 6 | pages = 983–993 | bibcode=2005PASJ...57..983Y| doi = 10.1093/pasj/57.6.983 | doi-access = free }}</ref> </references>
{{Stars of Centaurus}}
[[Category:W Ursae Majoris variables]] [[Category:Objects with variable star designations|Centauri, RR]] [[Category:Hipparcos objects|069779]] [[Category:Henry Draper Catalogue objects|124689]] [[Category:F-type main-sequence stars]] [[Category:Durchmusterung objects|CD-57 5498]] [[Category:Centaurus]]