{{Short description|Star in the constellation Centaurus}} {{starbox begin | name=BV Centauri }} {{Starbox image | image = [[Image:BVCenLightCurve.png|250px]] | caption = A near infrared ([[Photometric system#Photometric letters|I band]]) [[light curve]] for BV Centauri from [[All Sky Automated Survey|''ASAS'']] data, adapted from Kiraga (2012)<ref name="Kiraga"/> }} {{starbox observe | epoch=J2000 | constell=[[Centaurus]] | ra={{RA|13|31|19.485}}<ref name=tycho2/> | dec={{DEC|-54|58|33.52}}<ref name=tycho2/> | appmag_v=10.7 to 14.0<ref name=GCVS/> }} {{starbox character | class=G5-G8IV-V (secondary)<ref name=Vogt1980/> | b-v = 0.77<ref name=Vogt1980/> | u-b = -0.22<ref name=Vogt1980/> | variable = [[SS Cygni star|SS Cyg]]<ref name=GCVS/> }} {{starbox astrometry | radial_v=-22.3<ref name=Watson2007/> | prop_mo_ra=-25.8<ref name=tycho2/> | prop_mo_dec=-1.4<ref name=tycho2/> | parallax=2.81 | p_error=0.38 | parallax_footnote=<ref name=ramsay/> | dist_ly = | dist_pc = | absmag_v = +3.0 - +5.8<ref name=ramsay/> }} {{Starbox orbit | period_unitless = {{nowrap|{{val|0.611|0.002}} days<ref name=Watson2007/>}} | axis_unitless = {{val|2.53|u=cm|e=11}} {{nowrap|(0.017 au)<ref name=Gilliland1982/>}} | inclination = {{val|53|4}},<ref name=Watson2007/> {{val|62|5}}<ref name=Gilliland1982/> | k1 = {{val|128|3}}<ref name=Gilliland1982/> | k2 = {{val|137.3|0.3}}<ref name=Watson2007/> }} {{Starbox detail | source = | component1 = Primary (white dwarf) | mass = 1.18{{±|0.28|0.16}}<ref name=Watson2007/> | radius = | luminosity = | gravity = 8.3<ref name=Sion2007/> | temperature = 40000 ± 1000<ref name=Sion2007/> | metal_fe = | rotational_velocity = 500 ± 100<ref name=Sion2007/> | age_myr = | component2 = Secondary | mass2 = 1.05{{±|0.23|0.14}}<ref name=Watson2007/> | radius2 = 1.41 ± 0.04<ref name=Gilliland1982/> | luminosity2 = | gravity2 = 3.5<ref name=Watson2007/> | temperature2 = 5250<ref name=Watson2007/> | metal2_fe = | rotational_velocity2 = | age_myr2 = }} {{starbox catalog | names=[[Variable star designation|BV]] Centauri, [[2MASS]] J13311951-5458335, [[AAVSO]] 1325-54<ref name=SIMBAD/> }} {{Starbox reference|Simbad=BV+Cen}} {{starbox end}}
'''BV Centauri''' is a [[cataclysmic variable]] [[binary star]] in the [[constellation]] [[Centaurus]]. It is a [[dwarf nova]], and undergoes rapid increases in brightness that are recurrent with a mean period of 150 days. This period seems to have increased in the last few decades.<ref name=Plummer2009/> During quiescence, its visual [[apparent magnitude]] is about 13, with variations of a few tenths of magnitude over an orbit due to differences in the star's visible surface area ([[Ellipsoidal variable|ellipsoidal variability]]),<ref name=Gilliland1982/> brightening to a maximum magnitude of 10.7 during outbursts.<ref name=GCVS/> From its luminosity, it is estimated that the system is about {{convert|500|pc|ly}} away from Earth.<ref name=Vogt1980/><ref name=Gilliland1982/> A [[Gaia (spacecraft)|Gaia]] parallax of 2.81 [[arc-second|mas]] has been measured, corresponding to about 360 pc.<ref name=ramsay/> William Francis Herschel Waterfield discovered that the star is a [[variable star]], in 1929.<ref name="Waterfield1929"/>
Cataclysmic variables are short-period binary systems in which a [[white dwarf]] primary [[Accretion (astrophysics)|accretes]] matter from a secondary star. For BV Centauri, the white dwarf and its companion have estimated masses of 1.18 and 1.05 times the [[solar mass|mass of the Sun]] respectively,<ref name=Watson2007/> although alternate, conflicting mass measurements were reported too.<ref name=xu2019/> The secondary is a conventional star with a [[stellar classification|spectral type]] of G5-G8IV-V and it is assumed to contribute to half of the visual luminosity of the system. It is thought to have a radius of {{solar radius|1.4}} and so to be significantly evolved away from the [[zero age main sequence]].<ref name=Vogt1980/><ref name=Gilliland1982/> The reconstruction of its surface by [[Doppler imaging]] revealed it to be a highly magnetically active star, with about 25% of its surface covered in [[starspot]]s which are much more abundant on the hemisphere facing the white dwarf. Furthermore, a [[solar prominence|prominence]] was detected above the secondary star's surface, also in the side facing the white dwarf.<ref name=Watson2007/> The white dwarf primary can be observed clearly at [[ultraviolet]] wavelengths where it is the strongest source. Any [[accretion disk]] in the system appears relatively faint.<ref name=Sion2007/>
The system has a [[orbital period|period]] of 0.611179 days (16.7 hours), one of the longest periods for a dwarf nova, and is [[inclination|inclined]] by 53 ± 4° in relation to the plane of the sky.<ref name=Watson2007/>
It has been noted that BV Centauri's [[light curve]] during outbursts has anomalous behavior for a dwarf nova, with a long interval of up to 15 days before reaching peak brightness and no plateau at maximum brightness, and it has been compared to the [[nova|classic nova]] [[GK Persei]]. Based on this, it has been proposed that BV Centauri could have generated an unobserved nova outburst in the 19th century, which was missed by the observers at the time.<ref name=Plummer2009/><ref name=Menzies1986/>
==References== <references> <ref name="Kiraga">{{cite journal |last1=Kiraga |first1=M. |title=ASAS Photometry of ROSAT Sources. I. Periodic Variable Stars Coincident with Bright Sources from the ROSAT All Sky Survey |journal=Acta Astronomica |date=March 2012 |volume=62 |issue=1 |pages=67–95 |arxiv=1204.3825 |bibcode=2012AcA....62...67K |url=https://ui.adsabs.harvard.edu/abs/2012AcA....62...67K |access-date=28 November 2021}}</ref>
<ref name="Waterfield1929">{{cite journal |last1=Waterfield |first1=W. F. H. |title=Twenty-five New Variable Stars in Centaurus |journal=Harvard College Observatory Bulletin |date=January 1929 |volume=863 |page=6 |url=https://articles.adsabs.harvard.edu/pdf/1929BHarO.863....6W |access-date=14 January 2025}}</ref>
<ref name=Watson2007>{{cite journal|title=Roche tomography of cataclysmic variables - IV. Star-spots and slingshot prominences on BV Cen|journal=Monthly Notices of the Royal Astronomical Society|volume=382|issue=3|pages=1105–1118|date=December 2007|bibcode=2007MNRAS.382.1105W|doi=10.1111/j.1365-2966.2007.12173.x|last1=Watson|first1=C. A|last2=Steeghs|first2=D|last3=Shahbaz|first3=T|last4=Dhillon|first4=V. S|doi-access=free |arxiv=0707.0739|s2cid=2073273}}</ref>
<ref name=Plummer2009>{{cite journal|title=The Changing Nature of the Dwarf Nova BV Centauri|journal=The Journal of the American Association of Variable Star Observers|volume=37|issue=1|page=23|date=June 2009|bibcode=2009JAVSO..37...23P|last1=Plummer|first1=A|last2=Horn|first2=P}}</ref>
<ref name=Sion2007>{{cite journal|title=FUSE Observations of the Dwarf Novae UU Aql, BV Cen, and CH UMa in Quiescence|journal=The Astronomical Journal|volume=134|issue=2|pages=886–895|date=August 2007|bibcode=2007AJ....134..886S|doi=10.1086/518829|last1=Sion|first1=Edward M|last2=Godon|first2=Patrick|last3=Cheng|first3=Fuhua|last4=Szkody|first4=Paula|arxiv=0704.1133|s2cid=14393007}}</ref>
<ref name=Menzies1986>{{cite journal|title=BV Centauri - Dwarf or classical nova?|journal=Astrophysics and Space Science|volume=122|issue=1|pages=73–80|date=May 1986|bibcode=1986Ap&SS.122...73M|doi=10.1007/BF00654382|last1=Menzies|first1=J. W|last2=Odonoghue|first2=D|last3=Warner|first3=B|s2cid=123400202|url=https://link.springer.com/article/10.1007/BF00654382|url-access=subscription}}</ref>
<ref name=Vogt1980>{{cite journal|title=The dwarf nova BV Centauri - A spectroscopic binary|journal=Astrophysical Journal|volume=235|pages=945–954|date=February 1980|bibcode=1980ApJ...235..945V|doi=10.1086/157699|last1=Vogt|first1=N|last2=Breysacher|first2=J|doi-access=free}}</ref>
<ref name=Gilliland1982>{{cite journal|author=Gilliland, R. L.|title=A time-resolved spectroscopic study and modeling of the dwarf nova BV Centauri|journal=Astrophysical Journal|volume=263|pages=302–311|date=December 1982|bibcode=1982ApJ...263..302G|doi=10.1086/160504}}</ref>
<ref name=GCVS>{{cite journal|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS |volume=1|date=January 2009|bibcode=2009yCat....102025S|last1=Samus|first1=N. N|last2=Durlevich|first2=O. V|display-authors=etal}} [http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ5a206ac851ea&-out.add=.&-source=B/GCVS/gcvs_cat&recno=10176 VizieR table entry]</ref>
<ref name=tycho2>{{cite journal|bibcode= 2000A&A...355L..27H |title= The Tycho-2 catalogue of the 2.5 million brightest stars |journal= Astronomy and Astrophysics |volume= 355 |pages= L27 |last1= Høg |first1= E |last2= Fabricius |first2= C |last3= Makarov |first3= V. V |last4= Urban |first4= S |last5= Corbin |first5= T |last6= Wycoff |first6= G |last7= Bastian |first7= U |last8= Schwekendiek |first8= P |last9= Wicenec |first9= A |year= 2000 }}</ref>
<ref name=SIMBAD>{{cite simbad | title=V* BV Cen -- Dwarf Nova | access-date=2017-11-07}}</ref>
<ref name=ramsay>{{cite journal|bibcode=2017A&A...604A.107R|arxiv=1704.00496|title=Distances of cataclysmic variables and related objects derived from Gaia Data Release 1|journal=Astronomy & Astrophysics|volume=604|pages=A107|last1=Ramsay|first1=Gavin|last2=Schreiber|first2=Matthias R|last3=Gänsicke|first3=Boris T|last4=Wheatley|first4=Peter J|year=2017|doi=10.1051/0004-6361/201730679|s2cid=56464882}}</ref>
<ref name=xu2019>{{cite journal |arxiv=1905.03399 |doi=10.3847/1538-4357/ab1fe1 |title=The Fe Line Flux Ratio as a Diagnostic of the Maximum Temperature and the White Dwarf Mass of Cataclysmic Variables |year=2019 |last1=Xu |first1=Xiao-jie |last2=Yu |first2=Zhuo-li |last3=Li |first3=Xiang-Dong |journal=The Astrophysical Journal |volume=878 |issue=1 |page=53 |bibcode=2019ApJ...878...53X |s2cid=148571913 |doi-access=free }}</ref> </references>
{{Stars of Centaurus}}
[[Category:Centaurus]] [[Category:Dwarf novae]] [[Category:Objects with variable star designations|Centauri, BV]] [[Category:G-type subgiants]]