{{short description|Binary star system 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=λ Librae |x=195|y=545 }} | caption = Location of λ Librae (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Libra (constellation)|Libra]] | ra = {{RA|15|53|20.05463}}<ref name=vanLeeuwen2007/> | dec = {{DEC|−20|10|01.4177}}<ref name=vanLeeuwen2007/> | appmag_v = 5.03<ref name=apjs15/> }} {{Starbox character | class = B3 V<ref name=houk1978/> | b-v = −0.023<ref name=apjs15/> | u-b = −0.584<ref name=apjs15/> | r-i = | variable = [[Rotating ellipsoidal variable|Rotating ellipsoidal]]<ref name=Hoffleit1996/> }} {{Starbox astrometry | radial_v = {{Val|−2.0|0.5}}<ref name=deBruijne2012/> | prop_mo_ra = −9.81<ref name=vanLeeuwen2007/> | prop_mo_dec = −26.85<ref name=vanLeeuwen2007/> | parallax = 10.54 | p_error = 0.91 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = 0.56<ref name=Gontcharov2012/> }} {{Starbox orbit | reference = <ref name=Pourbaix2004/> | period_unitless = {{Val|14.4829|0.0004|u=d}} | eccentricity = {{Val|0.27|0.09}} | periastron = {{nowrap|2435172.380 ± 0.664 JD}} | periarg = {{Val|217|17}} | k1 = {{Val|28.5|3.3}} }} {{Starbox detail | source = | mass = {{Val|5.01|0.26}}<ref name=Hohle2010/> | radius = 3.9<ref name=PasinettiFracassini2001/> | luminosity = 743<ref name=Hohle2010/> | temperature = 18,700<ref name=Hohle2010/> | gravity = 4.75 | metal_fe = −0.27 | rotational_velocity = 155<ref name=Abt2002/> | age_myr = 282<ref name=Gontcharov2012/> }} {{Starbox catalog | names = [[Bayer designation|λ Lib]], [[Flamsteed designation|45 Lib]], [[Durchmusterung|BD]]−19°4249, [[FK5]] 1415, [[Henry Draper Catalogue|HD]] 142096, [[Hipparcos Catalogue|HIP]] 77811, [[Harvard Revised catalogue|HR]] 5902, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 183895.<ref name=SIMBAD/> }} {{Starbox reference | Simbad = lam+Lib }} {{Starbox end}} '''λ Librae''' (Latinised as '''Lambda Librae''') is the [[Bayer designation]] for a [[binary star]] system in the [[zodiac]] [[constellation]] of [[Libra (constellation)|Libra]]. It can be faintly seen with the naked eye, having an [[apparent visual magnitude]] of 5.03.<ref name=apjs15/> With an annual [[stellar parallax|parallax shift]] of 10.54 [[milliarcsecond|mas]],<ref name=vanLeeuwen2007/> it is roughly 310 [[light year]]s from the [[Sun]]. At that distance, the visual magnitude of this system is diminished by an [[extinction (astronomy)|extinction factor]] of 0.22 due to [[interstellar dust]].<ref name=Gontcharov2012/> It is 0.1 degree north of the ecliptic.
[[File:LamLibLightCurve.png|thumb|left|250px|A [[light curve]] for Lambda Librae, adapted from Wraight ''et al.'' (2012)<ref name="Wraight"/>]]
This is a single-lined [[spectroscopic binary]] star system with an [[orbital period]] of 14.48 days and an [[orbital eccentricity|eccentricity]] of 0.27.<ref name=Pourbaix2004/> The visible component is a [[B-type main sequence star]] with a [[stellar classification]] of B3 V.<ref name=houk1978/> It is a helium-weak [[chemically peculiar star]]<ref name=Renson2009/> and a [[rotating ellipsoidal variable]].<ref name=Hoffleit1996/> The star has an estimated 3.9<ref name=PasinettiFracassini2001/> times the [[solar radius|radius of the Sun]] and five times the [[solar mass|Sun's mass]].<ref name=Hohle2010/> This is a candidate [[Vega]]-like star, meaning that it shows an [[infrared excess]] characteristic of a circumstellar [[debris disk]].<ref name=Saffe2008/> The system is a source of [[X-ray astronomy|X-ray emission]].<ref name=Berghoefer1996/> {{clear left}} ==References== <references>
<ref name="Wraight">{{cite journal | last1=Wraight | first1=K. T. | last2=Fossati | first2=L. | last3=Netopil | first3=M. | last4=Paunzen | first4=E. | last5=Rode-Paunzen | first5=M. | last6=Bewsher | first6=D. | last7=Norton | first7=A. J. | last8=White | first8=Glenn J. | title=A photometric study of chemically peculiar stars with the STEREO satellites – I. Magnetic chemically peculiar stars | journal=Monthly Notices of the Royal Astronomical Society |date=February 2012 | volume=420 |issue=1 | pages=757–772 | doi=10.1111/j.1365-2966.2011.20090.x | doi-access=free | arxiv=1110.6283 | bibcode=2012MNRAS.420..757W }}</ref>
<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=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=PasinettiFracassini2001>{{citation | last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L. | last3=Covino | first3=S. | last4=Pozzi | first4=A. | title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) – Third edition – Comments and statistics | journal=Astronomy and Astrophysics | display-authors=1 | volume=367 | pages=521–524 | date=February 2001 | issue=2 | doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P | arxiv=astro-ph/0012289 | s2cid=425754 | postscript=. }}</ref>
<ref name=Berghoefer1996>{{citation | title=The ROSAT all-sky survey catalogue of optically bright OB-type stars | last1=Berghoefer | first1=T. W. | last2=Schmitt | first2=J. H. M. M. | last3=Cassinelli | first3=J. P. | journal=Astronomy and Astrophysics Supplement | volume=118 | pages=481–494 | date=September 1996 | issue=3 | doi=10.1051/aas:1996213 | bibcode=1996A&AS..118..481B | postscript=. | doi-access=free }}</ref>
<ref name=Hoffleit1996>{{citation | title=A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars | last1=Hoffleit | first1=Dorrit | journal=The Journal of the American Association of Variable Star Observers | volume=24 | issue=2 | pages=105–116 | year=1996 | bibcode=1996JAVSO..24..105H | postscript=. }}</ref>
<ref name=Pourbaix2004>{{citation | title=S<sub>B<sup>9</sup></sub>: The ninth catalogue of spectroscopic binary orbits | journal=Astronomy & Astrophysics |display-authors=5 | 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. | volume=424 | issue=2 | pages=727–732 | date=2004 | doi=10.1051/0004-6361:20041213 | bibcode=2004A&A...424..727P | arxiv=astro-ph/0406573 | s2cid=119387088 | postscript=. }}</ref>
<ref name=Renson2009>{{citation | last1=Renson | first1=P. | last2=Manfroid | first2=J. | title=Catalogue of Ap, HgMn and Am stars | journal=Astronomy and Astrophysics | postscript=. | volume=498 | issue=3 | pages=961–966 |date=May 2009 | doi=10.1051/0004-6361/200810788 | bibcode=2009A&A...498..961R | url=https://zenodo.org/record/890529| doi-access=free }}</ref>
<ref name=Hohle2010>{{citation | 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=Gontcharov2012>{{citation | title=Spatial distribution and kinematics of OB stars | last1=Gontcharov | first1=G. A. | journal=Astronomy Letters | volume=38 | issue=11 | pages=694–706 | date=November 2012 | doi=10.1134/S1063773712110035 | bibcode=2012AstL...38..694G | arxiv=1606.09028 | s2cid=119108982 | 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=houk1978>{{citation | last1=Houk | first1=Nancy | last2=Smith-Moore | first2=M. | title=Michigan catalogue of two-dimensional spectral types for the HD stars | volume=4 | publication-place=Ann Arbor | year=1978 | publisher=Dept. of Astronomy, University of Michigan | bibcode=1988mcts.book.....H | postscript=. }}</ref>
<ref name=Abt2002>{{citation | display-authors=1 | last1=Abt | first1=Helmut A. | last2=Levato | first2=Hugo | last3=Grosso | first3=Monica | title=Rotational Velocities of B Stars | journal=The Astrophysical Journal | volume=573|pages=359–365 | year=2002 | issue=1 | postscript=. | bibcode=2002ApJ...573..359A | doi=10.1086/340590 | 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>{{citation | title=lam Lib -- Spectroscopic binary | work=SIMBAD Astronomical Database | publisher=[[Centre de Données astronomiques de Strasbourg]] | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=lam+Lib | accessdate=2017-01-30 | postscript=. }}</ref>
</references>
{{Stars of Libra|state=collapsed}}
{{DEFAULTSORT:Lambda Librae}} [[Category:B-type main-sequence stars]] [[Category:Spectroscopic binaries]] [[Category:Helium-weak stars]] [[Category:Libra (constellation)]] [[Category:Bayer objects|Librae, Lambda]] [[Category:Durchmusterung objects|BD-19 4249]] [[Category:Flamsteed objects|Librae, 45]] [[Category:Henry Draper Catalogue objects|142096]] [[Category:Hipparcos objects|077811]] [[Category:Bright Star Catalogue objects|5902]] [[Category:Rotating ellipsoidal variables]]