{{Short description|Binary star system in the constellation Lupus}} {{DISPLAYTITLE:Tau<sup>2</sup> Lupi}} {{other stars by Bayer designation|Tau Lupi{{!}}τ Lupi}} {{Starbox begin | name = Tau<sup>2</sup> Lupi }} {{Starbox image | image = {{Location mark |image=Lupus constellation map.svg|alt=|float=center|width=250 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=Tau2 Lupi |x=860|y=870 }} | caption = Location of τ<sup>2</sup> Lupi (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Lupus (constellation)|Lupus]] | ra = {{RA|14|26|10.81378}}<ref name=vanLeeuwen2007/> | dec = {{DEC|−45|22|45.4023}}<ref name=vanLeeuwen2007/> | appmag_v = 4.34<ref name=Mermilliod1986/> {{nowrap|(4.93 + 5.55)}}<ref name=Eggleton2008/> }} {{Starbox character | class = {{nowrap|F4 IV + A7:}}<ref name=Eggleton2008/> | b-v = +0.43<ref name=Mermilliod1986/> | u-b = +0.16<ref name=Mermilliod1986/> | r-i = | variable = }} {{Starbox astrometry | radial_v = {{Val|−0.60|1.60}}<ref name=deBruijne2012/> | prop_mo_ra = +14.62<ref name=vanLeeuwen2007/> | prop_mo_dec = −7.33<ref name=vanLeeuwen2007/> | parallax = 10.22 | p_error = 0.31 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = −0.62<ref name=Anderson2012/> }} {{Starbox orbit | reference = <ref name=Heintz1986/> | period = 26.2 | axis = 0.125 | eccentricity = 0.94 | inclination = 56.0 | node = 175.7 | periastron = 1969.1 | periarg = 191.0 }} {{Starbox detail | source = | mass = | radius = | luminosity = 150<ref name=Anderson2012/> | temperature = | gravity = | metal_fe = | rotational_velocity = 0<ref name=Uesugi1970/> | rotation = | age_myr = }} {{Starbox catalog | names = [[Bayer designation|τ<sup>2</sup> Lup]], [[Durchmusterung|CD]]−44°9323, [[Henry Draper Catalogue|HD]] 126354, [[Hipparcos Catalogue|HIP]] 70576, [[Harvard Revised catalogue|HR]] 5396, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 224920<ref name=SIMBAD/> }} {{Starbox reference | Simbad = tau02+Lup }} {{Starbox end}} '''Tau<sup>2</sup> Lupi''', [[Latinisation of names|Latinized]] from '''τ<sup>2</sup> Lup''', is a [[binary star]]<ref name=Eggleton2008/> system in the [[constellation]] [[Lupus (constellation)|Lupus]]. It is visible to the naked eye with a combined [[apparent visual magnitude]] of 4.34.<ref name=Mermilliod1986/> Based upon an annual [[stellar parallax|parallax shift]] of 10.22<ref name=vanLeeuwen2007/> [[milliarcsecond|mas]] as seen from Earth, it is located around 319 [[light year]]s from the [[Sun]]. The two components orbit each other with a [[orbital period|period]] of 26.2 years and a high [[orbital eccentricity|eccentricity]] of 0.94.<ref name=Heintz1986/> The brighter component is a magnitude 4.93 [[subgiant star]] with a [[stellar classification]] of F4 IV. Its companion is an [[A-type star]] with visual magnitude 5.55 and class A7:.<ref name=Eggleton2008/>
==References== <references>
<ref name=vanLeeuwen2007>{{citation | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | date=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}</ref>
<ref name=Anderson2012>{{citation | title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | s2cid=119257644 | postscript=. }}</ref>
<ref name=Heintz1986>{{citation | title=Orbits of 20 visual binaries | last1=Heintz | first1=W. D. | journal=Astronomy and Astrophysics Supplement Series | volume=65 | issue=2 | date=August 1986 | pages=411–417 | bibcode=1986A&AS...65..411H | postscript=. }}</ref>
<ref name=Eggleton2008>{{citation | 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 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | s2cid=14878976 | postscript=. }}</ref>
<ref name=deBruijne2012>{{citation | last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C. | title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project | journal=Astronomy & Astrophysics | volume=546 | id=A61 | pages=14 | date=October 2012 | doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D | arxiv=1208.3048 | s2cid=59451347 | postscript=. }}</ref>
<ref name=Uesugi1970>{{citation | last1=Uesugi | first1=Akira | last2=Fukuda | first2=Ichiro | title=Catalogue of rotational velocities of the stars | journal=Contributions from the Institute of Astrophysics and Kwasan Observatory | date=1970 | publisher=University of Kyoto | bibcode=1970crvs.book.....U | postscript=. }}</ref>
<ref name=Mermilliod1986>{{citation | last1=Mermilliod | first1=J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV Data | year=1986 | publisher=[[SIMBAD]] | bibcode=1986EgUBV........0M | postscript=. }}</ref>
<ref name=SIMBAD>{{cite simbad | title=tau02 Lup | access-date=2017-03-10 }}</ref>
</references>
{{Stars of Lupus|state=collapsed}}
[[Category:F-type subgiants]] [[Category:Lupus (constellation)]] [[Category:Bayer objects|Lupi, Tau2]] [[Category:Henry Draper Catalogue objects|126354]] [[Category:Hipparcos objects|070576]] [[Category:Bright Star Catalogue objects|5396]] [[Category:Binary stars]] [[Category:Durchmusterung objects|CD-44 09323]]