{{short description|Star in the constellation Libra}} {{Starbox begin}} {{Starbox image | image = {{Location mark |image=Libra constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=τ Librae |x=318|y=840 }} | caption = Location of τ Librae (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Libra (constellation)|Libra]] | ra = {{RA|15|38|39.36950}}<ref name=vanLeeuwen2007/> | dec = {{DEC|−29|46|39.8956}}<ref name=vanLeeuwen2007/> | appmag_v = 3.68<ref name=apjs15/> }} {{Starbox character | class = B2.5 V<ref name=Hiltner2969/> | b-v = −0.179<ref name=apjs15/> | u-b = −0.717<ref name=apjs15/> | r-i = | variable = }} {{Starbox astrometry | radial_v = {{Val|+33.3|2.3}}<ref name=Jilinski2006/> | prop_mo_ra = −22.08<ref name=vanLeeuwen2007/> | prop_mo_dec = −24.46<ref name=vanLeeuwen2007/> | parallax = 8.89 | p_error = 0.20 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = −1.59<ref name=Anderson2012/> }} {{Starbox orbit | reference = <ref name=Pourbaix2004/> | period_unitless = 3.2907 d | eccentricity = 0.28 | node = 114 | periastron = 2439272.312 JD | k1 = 75 | k2 = 167 }} {{Starbox detail | source = | component1 = τ Lib A | mass = {{Val|7.25|0.49}}<ref name=Hohle2010/> | radius = 3.2<ref name=PasinettiFracassini2001/> | luminosity_bolometric = 2,705<ref name=Hohle2010/> | temperature = 17,990<ref name=Saffe2008/> | gravity = 4.33<ref name=Saffe2008/> | metal_fe = +0.17<ref name=Saffe2008/> | rotational_velocity = 134<ref name=Jilinski2006/> | age_myr = {{Val|31.5|5.6}}<ref name=Tetzlaff2011/> }} {{Starbox catalog | names = [[Bayer designation|τ Lib]], [[Flamsteed designation|40 Lib]], [[Durchmusterung|CD]]−29°11837, [[Henry Draper Catalogue|HD]] 139365, [[Hipparcos Catalogue|HIP]] 76600, [[Harvard Revised catalogue|HR]] 5812, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 183649<ref name=SIMBAD/> }} {{Starbox reference | Simbad = tau+Lib }} {{Starbox end}} '''Tau Librae''', [[Latinisation of names|Latinized]] from τ Librae, is a [[binary star]] system at the southern edge of the [[zodiac]] [[constellation]] of [[Libra (constellation)|Libra]]. It can be seen with the naked eye, having an [[apparent visual magnitude]] of 3.68.<ref name=apjs15/> The distance to this system is around 367 [[light year]]s, as determined from an annual [[stellar parallax|parallax shift]] of 8.89 [[milliarcsecond|mas]].<ref name=vanLeeuwen2007/>
Judging by its motion through space and physical properties, this system is a member of the Upper Centaurus–Lupus group of the [[Scorpius–Centaurus association]].<ref name=Jilinski2006/> It is a double-lined [[spectroscopic binary]]<ref name=Strom2005/> with an [[orbital period]] of just 3.3 days and an [[orbital eccentricity|eccentricity]] of 0.28.<ref name=Pourbaix2004/> The primary, component A, is a [[B-type main sequence star]] with a [[stellar classification]] of B2.5 V.<ref name=Hiltner2969/> It is estimated to hold more than seven times the [[solar mass|mass of the Sun]]<ref name=Hohle2010/> and have over three times the [[solar radius|Sun's radius]].<ref name=PasinettiFracassini2001/> It is only 31.5 million years old<ref name=Tetzlaff2011/> and is spinning relatively rapidly with a [[projected rotational velocity]] of 134 km/s.<ref name=Jilinski2006/> It is a [[heartbeat star]] system, with pulsations caused by tidal forces.<ref name=Sharma>{{cite journal|doi=10.1093/mnras/stac1816 |title=Pulsating B stars in the Scorpius–Centaurus Association with TESS |year=2022 |last1=Sharma |first1=Awshesh N. |last2=Bedding |first2=Timothy R. |last3=Saio |first3=Hideyuki |last4=White |first4=Timothy R. |journal=Monthly Notices of the Royal Astronomical Society |volume=515 |issue=1 |pages=828–840 |doi-access=free |arxiv=2203.02582 | bibcode=2022MNRAS.515..828S}}</ref>
The system is emitting an [[infrared excess]], suggesting the presence of a [[circumstellar disk]] of material.<ref name=Saffe2008/>
==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=PasinettiFracassini2001>{{citation | first1=L. E. | last1=Pasinetti-Fracassini | first2=L. | last2=Pastori | first3=S. | last3=Covino | first4=A. | last4=Pozzi | title=Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS) | edition=3rd | display-authors=1 | postscript=. | journal=Astronomy and Astrophysics | volume=367 | pages=521–524 | date=February 2001 | doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P |arxiv = astro-ph/0012289 | s2cid=425754 }}</ref>
<ref name=Tetzlaff2011>{{citation | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=410 | issue=1 | pages=190–200 | date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T | arxiv=1007.4883 | s2cid=118629873 | postscript=. }}</ref>
<ref name=Hohle2010>{{citation | display-authors=1 | last1=Hohle | first1=M. M. | last2=Neuhäuser | first2=R. | last3=Schutz | first3=B. F. | title=Masses and luminosities of O- and B-type stars and red supergiants | journal=Astronomische Nachrichten | volume=331 | issue=4 | page=349 | date=April 2010 | doi=10.1002/asna.200911355 | bibcode=2010AN....331..349H | arxiv=1003.2335 | s2cid=111387483 | postscript=. }}</ref>
<ref name=Saffe2008>{{citation | title=Spectroscopic metallicities of Vega-like stars | last1=Saffe | first1=C. | last2=Gómez | first2=M. | last3=Pintado | first3=O. | last4=González | first4=E. | journal=Astronomy and Astrophysics | postscript=. | volume=490 | issue=1 | pages=297–305 | date=October 2008 | doi=10.1051/0004-6361:200810260 | bibcode=2008A&A...490..297S |arxiv = 0805.3936 | s2cid=15059920 }}</ref>
<ref name=Jilinski2006>{{citation | display-authors=1 | last1=Jilinski | first1=E. | last2=Daflon | first2=S. | last3=Cunha | first3=K. | last4=de La Reza | first4=R. | title=Radial velocity measurements of B stars in the Scorpius–Centaurus association | journal=Astronomy and Astrophysics | volume=448 | issue=3 |date=March 2006 | pages=1001–1006 | doi=10.1051/0004-6361:20041614 | bibcode=2006A&A...448.1001J | arxiv=astro-ph/0601643 | s2cid=17818058 | postscript=. }}</ref>
<ref name=Pourbaix2004>{{citation | display-authors=1 | last1=Pourbaix | first1=D. | last2=Tokovinin | first2=A. A. | last3=Batten | first3=A. H. | last4=Fekel | first4=F. C. | last5=Hartkopf | first5=W. I. | last6=Levato | first6=H. | last7=Morrell | first7=N. I. | last8=Torres | first8=G. | last9=Udry | first9=S. | title=SB9: The ninth catalogue of spectroscopic binary orbits | journal=Astronomy and Astrophysics | volume=424 | issue=2 | pages=727–732 | year=2004 | bibcode=2004A&A...424..727P | doi=10.1051/0004-6361:20041213 | arxiv=astro-ph/0406573 | s2cid=119387088 | postscript=. }}</ref>
<ref name=Strom2005>{{citation | title=B Star Rotational Velocities in h and χ Persei: A Probe of Initial Conditions during the Star Formation Epoch? | display-authors=1 | last1=Strom | first1=Stephen E. | last2=Wolff | first2=Sidney C. | last3=Dror | first3=David H. A. | journal=The Astronomical Journal | volume=129 | issue=2 | pages=809–828 | date=February 2005 | doi=10.1086/426748 | bibcode=2005AJ....129..809S | postscript=. |arxiv = astro-ph/0410337 | s2cid=15059129 }}</ref>
<ref name=Hiltner2969>{{citation | last1=Hiltner | first1=W. A. | last2=Garrison | first2=R. F. | last3=Schild | first3=R. E. | date=July 1969 | title=MK Spectral Types for Bright Southern OB Stars | journal=Astrophysical Journal | volume=157 | pages=313–326 | doi=10.1086/150069 | bibcode=1969ApJ...157..313H | postscript=. | doi-access=free }}</ref>
<ref name=apjs15>{{citation | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=Hugo | title=A photometric investigation of the Scorpio-Centaurus association | journal=Astrophysical Journal Supplement | postscript=. | volume=15 | page=459 | date=June 1968 | bibcode=1968ApJS...15..459G | doi=10.1086/190168 | doi-access=free }}</ref>
<ref name=SIMBAD>{{cite simbad | title=tau Lib | accessdate=2017-01-30 | postscript=. }}</ref>
</references>
==External links== *{{citation | first1=James B. | last1=Kaler | date=May 17, 2013 | title=Tau Librae | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/taulib.html | accessdate=2017-02-02 | postscript=. }}
{{Stars of Libra|state=collapsed}}
{{DEFAULTSORT:Tau Librae}} [[Category:B-type main-sequence stars]] [[Category:Bayer objects|Librae, Tau]] [[Category:Libra (constellation)]] [[Category:Flamsteed objects|Librae, 40]] [[Category:Durchmusterung objects|CD-29 11837]] [[Category:Henry Draper Catalogue objects|139365]] [[Category:Hipparcos objects|076600]] [[Category:Bright Star Catalogue objects|5812]] [[Category:Upper Centaurus Lupus]] [[Category:Spectroscopic binaries]]