Y Centauri

{{Short description|Variable star in the constellation Centaurus}} {{confuse|HD 120987{{!}}y Centauri|Gamma Centauri{{!}}γ Centauri|Upsilon Centauri{{!}}υ Centauri}} {{Starbox begin | name = Y Centauri }} {{Starbox image | image = [[Image:YCenLightCurve.png|250px]] | caption = A [[Photometric_system#Photometric_letters|visual band]] [[light curve]] for Y Centauri, plotted from [[All Sky Automated Survey|''ASAS'']] data<ref name=ASASServer/> }} {{Starbox observe | epoch=[[J2000.0]] | constell=[[Centaurus]] | ra={{RA|14|30|58.61656}}<ref name=hipparcos/> | dec={{DEC|-30|05|51.8706}}<ref name=hipparcos/> | appmag_v=8.0 - 9.1<ref name=gcvs/> }} {{Starbox character | type = [[asymptotic giant branch|AGB]]<ref name=yoon/> | class = M4e - M7<ref name=gcvs/> | b-v=+1.44<ref name=ducati/> | u-b=+0.72<ref name=ducati/> | variable = [[Semiregular variable star|SRb]]<ref name=gcvs/> }} {{Starbox astrometry | radial_v=−6.00<ref name=pulkovo/> | prop_mo_ra=−38.874<ref name=dr2/> | prop_mo_dec=−25.867<ref name=dr2/> | parallax= 4.4510 | p_error=0.2738 | parallax_footnote=<ref name=dr2/> }} {{Starbox detail | mass = | radius = 48<ref name=dr2/> | luminosity = 330<ref name=dr2/> | temperature = 3,557<ref name=dr2/> | gravity = −0.315<ref name=mcdonald2017/> }} {{Starbox catalog | names=[[Variable star designation|Y]] Cen, [[Henry Draper Catalogue|HD]] 127233, [[Cordoba Durchmusterung|BD]]−29°11116, [[Hipparcos catalogue|HIP]] 70969, [[Smithsonian Astrophysical Observatory catalogue|SAO]] 182618, [[Boss General Catalogue|GC]] 19563, [[IRAS]] 14280-2952, [[AAVSO]] 1425-29 }} {{Starbox reference | Simbad = Y+Centaurus }} {{Starbox end}}

'''Y Centauri''' or '''Y Cen''' (''HD 127233'', ''HIP 70969'') is a [[semiregular variable star]] in the constellation of [[Centaurus]].

The variability in the star was discovered by [[Williamina Fleming]] in 1895 and published in the ''Third Catalogue of Variable Stars''. The photographic magnitude range was given as 7.7 - 8.8, but the variability was described as "somewhat doubtful".<ref name=chandler/> It was later given the designation HV 52 in the Harvard Catalogue of Variable Stars.<ref name=pickering/> The [[General Catalogue of Variable Stars]] lists it as a semiregular variable star with a period of 180 days and a visual magnitude range of 8.0 - 9.1.<ref name=gcvs/> A study of [[Hipparcos satellite]] photometry found a small amplitude range of 0.2 magnitudes at a visual magnitude of 8.53.<ref name=koen/>

The distance of the star is poorly known. The revised Hipparcos annual parallax of 3.50 mas gives a distance of 900 light years.<ref name=hipparcos/> A study taking into account the variability of the star found a parallax of 5.57 mas, corresponding to a distance of 585 light years.<ref name=pourbaix/> Both estimates have a margin of error over 20%. The [[Gaia Data Release 2]] parallax lies between these two values and appears more accurate with a margin of error around 5%, but with a large value for astrometric noise.<ref name=dr2/> [[Gaia EDR3]] does not list a parallax for this star.<ref name=edr3/>

Y Centauri is an [[asymptotic giant branch]] star<ref name=yoon/> 330 times as luminous as the sun. Its spectral type varies between M4 and M7 as it pulsates.<ref name=gcvs/>

The star has been observed to produce 22 GHz water [[maser]] emission,<ref name=lewis/> although later searches did not find any maser emission.<ref name=yoon/>

==References== {{Reflist|refs=

<ref name=ASASServer>{{cite web |title=ASAS All Star Catalogue |url=http://www.astrouw.edu.pl/asas/?page=aasc |publisher=The All Sky Automated Survey |access-date=8 December 2021}}</ref>

<ref name=mcdonald2017>{{cite journal |bibcode=2017MNRAS.471..770M |title=Fundamental parameters and infrared excesses of Tycho-Gaia stars |last1=McDonald |first1=I. |last2=Zijlstra |first2=A. A. |last3=Watson |first3=R. A. |journal=Monthly Notices of the Royal Astronomical Society |volume=471 |issue=1 |pages=770 |year=2017 |arxiv=1706.02208 |doi=10.1093/mnras/stx1433 |doi-access=free |s2cid=73594365 }}</ref>

<ref name=yoon>{{cite journal|bibcode= 2014ApJS..211...15Y|title= SiO and H2O Maser Survey toward Post-asymptotic Giant Branch and Asymptotic Giant Branch Stars|journal= The Astrophysical Journal Supplement|volume= 211|pages= 15|last1= Yoon|first1= Dong-Hwan|last2= Cho|first2= Se-Hyung|last3= Kim|first3= Jaeheon|last4= Yun|first4= Young joo|last5= Park|first5= Yong-Sun|year= 2014|issue= 1|doi= 10.1088/0067-0049/211/1/15|s2cid= 73561291|doi-access= free}}</ref>

<ref name=pourbaix>{{cite journal|bibcode=2003A&A...399.1167P|title=How many Hipparcos Variability-Induced Movers are genuine binaries?|journal=Astronomy and Astrophysics|volume=399|issue=3|pages=1167–1176|last1=Pourbaix|first1=D.|last2=Platais|first2=I.|last3=Detournay|first3=S.|last4=Jorissen|first4=A.|last5=Knapp|first5=G.|last6=Makarov|first6=V. V.|year=2003|doi=10.1051/0004-6361:20021843|arxiv = astro-ph/0212201 |s2cid=17844733}}</ref>

<ref name=koen>{{cite journal|bibcode= 2002MNRAS.331...45K|title= New periodic variables from the Hipparcos epoch photometry|journal= Monthly Notices of the Royal Astronomical Society|volume= 331|pages= 45–59|last1= Koen|first1= Chris|last2= Eyer|first2= Laurent|year= 2002|issue= 1|doi= 10.1046/j.1365-8711.2002.05150.x|doi-access= free|arxiv = astro-ph/0112194 |s2cid= 10505995}}</ref>

<ref name=lewis>{{cite journal|last=Lewis|first=B. M.|journal=The Astrophysical Journal|date=October 1997|title=A renewed search for water maser emission from Mira Variables|volume=114|pages=1602–1606|doi=10.1086/118591|arxiv = astro-ph/9706207 |bibcode = 1997AJ....114.1602L |s2cid=119386147}}</ref>

<ref name=chandler>{{cite journal|bibcode=1896AJ.....16..145C|title=Third catalogue of variable stars|journal=Astronomical Journal|volume=16|pages=145|last1=Chandler|first1=S. C.|year=1896|doi=10.1086/102484}}</ref>

<ref name=pickering>{{cite journal|last=Pickering|first=Edward Charles|authorlink=Edward Charles Pickering|date=1905|title=Second supplement to Catalogue of Variable Stars|journal=Annals of Harvard College Observatory|volume=53|pages=143–153|bibcode = 1905AnHar..53..143P }}</ref>

<ref name=ducati>{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|pages=0|last1=Ducati|first1=J. R.|year=2002}}</ref>

<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|pages=02025|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009|display-authors=etal}}</ref>

<ref name=pulkovo>{{cite journal|bibcode=2006AstL...32..759G|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|last1=Gontcharov|first1=G. A.|year=2006|doi=10.1134/S1063773706110065|arxiv = 1606.08053 |s2cid=119231169}}</ref>

<ref name=hipparcos>{{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|last1=Van Leeuwen|first1=F.|year=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 |s2cid=18759600}}</ref>

}}

== Notes == {{notelist}}

[[Category:Centaurus]] [[Category:Semiregular variable stars]] [[Category:Objects with variable star designations|Centauri, Y]] [[Category:M-type giants]] [[Category:Asymptotic-giant-branch stars]] [[Category:Emission-line stars]] [[Category:Hipparcos objects|070969]] [[Category:Henry Draper Catalogue objects|127233]] [[Category:Durchmusterung objects]] [[Category:Astronomical objects discovered in 1895]] [[Category:Discoveries by Williamina Fleming]]