{{short description|Binary star in the constellation Libra}} {{Starbox begin | name=δ Librae }} {{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=δ Librae |x=585|y=175 }} | caption = Location of δ Librae (circled in red) }} {{Starbox observe | epoch=J2000 | ra={{RA|15|00|58.34830}}<ref name=dr3/> | dec={{DEC|-08|31|08.2104}}<ref name=dr3/> | appmag_v=4.93<ref name=Ducati2002/> | constell=[[Libra (constellation)|Libra]] }} {{Starbox character | type = [[main sequence]]<ref name=zorec2012/> | class=B9.5V<ref name=HD/> | b-v=+0.00<ref name=UBV/> | u-b=−0.10<ref name=UBV/> | variable=[[Algol variable|Algol eclipsing]]<ref name=magnitude/> }} {{Starbox astrometry | radial_v= {{Val|−38.7|2}}<ref name=GCRV/> | prop_mo_ra= −63.051<ref name=dr3/> | prop_mo_dec= −6.024<ref name=dr3/> | parallax= 9.2824 | p_error=0.4725 | parallax_footnote=<ref name=dr3/> | absmag_v=+0.15<ref name=Anderson2012/> }} {{Starbox orbit | axis_unitless = {{Val|12.73|0.34|ul=mas}}<ref name=Malkov2020/> | period_unitless = 2.3273543 days<ref name=Malkov2020/> | eccentricity = 0.07<ref name=Tomkin1978/> | k1 = 76.6<ref name=Tomkin1978/> | k2 = 218.7<ref name=Tomkin1978/> }} {{Starbox detail | source = <ref name=Malkov2020/> | component1 = δ Lib A | radius = {{Val|3.60|0.13}} | mass = {{Val|3.78|0.13}} | luminosity = {{Val|155|11|10}} | temperature = {{Val|10520|110|fmt=commas}} | age_gyr = 0.5<ref name=Rhee/> | component2 = δ Lib B | mass2 = {{Val|1.50|0.04}} | radius2 = {{val|3.79|0.04}} | luminosity2 = {{Val|9.1|1.4|1.2}} | temperature2 = {{Val|5150|175|fmt=commas}} }} {{Starbox catalog | names=δ Lib, Zuben Elakribi, [[Flamsteed designation|19]] Librae, {{nowrap|[[Bonner Durchmusterung|BD]]−07°3938}}, [[Henry Draper Catalogue|HD]] 132742, [[Hipparcos|HIP]] 73473, [[Bright Star Catalogue|HR]] 5586, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]] 140270 }} {{Starbox reference |Simbad=del+Lib }} {{Starbox end}}
'''Delta Librae''', [[Romanization of Greek|Latinized]] from δ Librae, is a [[variable star]] in the [[constellation]] [[Libra (constellation)|Libra]]. It has the traditional name ''Zuben Elakribi'', a variant of the traditional name of [[Gamma Librae]].<ref name=ACII/> With [[μ Virginis]] it forms one of the [[Akkadian language|Akkadian]] [[lunar mansion]]s ''Mulu-izi''<ref name=Allen/> (meaning "Man-of-fire").<ref name=Brown/>
[[File:DeltaLibLightCurve.png|thumb|left|250px|A [[light curve]] for Delta Librae, adapted from Shobbrook (2005)<ref name="Shobbrook"/>]]
δ Librae is approximately 350 [[light year]]s from the [[Earth]] and the primary, component A, belongs to the [[Stellar classification|spectral class]] B9.5V, indicating it is a [[B-type main-sequence star]]. It is visible to the naked eye with an [[apparent visual magnitude]] of 4.93<ref name=Ducati2002/> and is moving closer to the Sun with a [[radial velocity]] of −39 km/s.<ref name=GCRV/> This is an [[Algol]]-like [[eclipsing binary]] star system, with a [[orbital period|period]] of 2.3274 days and an [[orbital eccentricity|eccentricity]] of 0.07.<ref name=Tomkin1978/> Its [[apparent magnitude]] varies from 4.91 to 5.90.<ref name="gcvs"/> The secondary is filling its [[Roche lobe]] and there is evidence of large-scale mass transfer in the past, with the secondary being more [[stellar evolution|evolved]] than the primary despite now being less massive.<ref name=Tomkin1978/>
Along with [[λ Tauri]], it was one of the first stars on which rotational line broadening was observed, by [[Frank Schlesinger]] in 1911.<ref name="test"/> {{clear left}} ==References== {{Reflist|refs=
<ref name=dr3>{{cite Gaia DR3|6332277920392457472}}</ref>
<ref name="test">{{cite journal | last1=Schlesinger | first1=F. | year=1909 | bibcode=1911MNRAS..71..719S | title=Rotation of Stars about their Axes | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=71 | issue=9 | page=719 | doi=10.1093/mnras/71.9.719 | doi-access=free }}</ref>
<ref name=Malkov2020>{{Cite journal |last=Malkov |first=Oleg Yu |date=2020-02-01 |title=Semidetached double-lined eclipsing binaries: Stellar parameters and rare classes |journal=Monthly Notices of the Royal Astronomical Society |volume=491 |issue=4 |pages=5489–5497 |doi=10.1093/mnras/stz3363 |doi-access=free |bibcode=2020MNRAS.491.5489M |issn=0035-8711}}</ref>
<ref name="gcvs">{{cite journal | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | title=General Catalogue of Variable Stars | version=GCVS 5.1 | journal=Astronomy Reports | year=2017 | volume=61 | issue=1 | pages=80–88 | bibcode=2017ARep...61...80S | url=http://www.sai.msu.su/gcvs/cgi-bin/search.cgi?search=del+lib | accessdate=2018-01-07 | doi=10.1134/S1063772917010085 | s2cid=125853869 | url-access=subscription }}</ref>
<ref name=Brown>{{cite journal |author=Brown Jr., R. |year=1891 |title=Remarks on the Euphratean Astronomical Names of the Signs of the Zodiac |journal=Proceedings of the Society of Biblical Archaeology |volume=13 |page=194 }}</ref>
<ref name=Allen>{{cite book | last1=Allen | first1=R. H. | author-link=Richard Hinckley Allen | year=1963 | title=[[Star Names: Their Lore and Meaning]] | edition=[[Reprint|rep]]. | publisher=[[Dover Publications]] Inc. | location=[[New York City|New York]], [[New York (state)|NY]] | pages=277, 473 }}</ref>
<ref name=ACII>{{cite book |bibcode=1964ack..book.....B |year=1964 |title=Atlas coeli II - Katalog 1950.0 |last1=Becvar |first1=Antonin }}</ref>
<ref name=Rhee>{{cite journal | title=Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs | author1=Rhee, Joseph H.|author2=Song, Inseok|author3=Zuckerman, B.|author4=McElwain, Michael | journal=The Astrophysical Journal|volume=660|issue=2|pages=1556–1571|date=2007 | bibcode=2007ApJ...660.1556R|doi=10.1086/509912|arxiv=astro-ph/0609555|s2cid=11879505}}</ref>
<ref name=Tomkin1978>{{cite journal | title=Secondaries of eclipsing binaries. I. Detection of the secondary of Delta Librae | last1=Tomkin | first1=J. | journal=Astrophysical Journal | volume=221 | pages=608–615 | date=April 1978 | doi=10.1086/156064 | bibcode=1978ApJ...221..608T | doi-access=free }}</ref>
<ref name=Anderson2012>{{cite journal | 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 }}</ref>
<ref name=UBV>{{cite journal | title=UBVRIJKL Photometry of the Bright Stars|author1=Johnson, H. L. |journal=Communications of the Lunar and Planetary Laboratory|volume=4 | date=1966|page=99|bibcode=1966CoLPL...4...99J}}</ref>
<ref name=magnitude>{{cite web | title=Del Lib |url = http://www.aavso.org/vsx/index.php?view=detail.top&oid=17591 | work=The International Variable Star Index | publisher=AAVSO – American Association of Variable Star Observers | access-date=27 September 2017 }}</ref>
<ref name=GCRV>{{cite journal | title=General catalogue of stellar radial velocities|author=Wilson, Ralph Elmer | journal=Carnegie Institute Washington D.C. Publication|date=1953 | bibcode=1953GCRV..C......0W}}</ref>
<ref name=HD>{{cite journal | bibcode=1999MSS...C05....0H | title=Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5 | journal=Michigan Spectral Survey|volume=5|author1=Houk, N.|author2=Swift, C.|year=1999}}</ref>
<ref name=Ducati2002>{{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|author1=Ducati, J. R.|year=2002}}</ref>
<ref name="Shobbrook">{{cite journal | last1=Shobbrook |first1=R. R. | title=Photometry of 20 eclipsing and ellipsoidal binary systems | journal=The Journal of Astronomical Data |date=December 2005 |volume=11 | page=7 | bibcode=2005JAD....11....7S }}</ref>
<ref name=zorec2012>{{cite journal |last1=Zorec |first1=J. |last2=Royer |first2=F. |title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities |journal=Astronomy and Astrophysics |date=2012 |volume=537 |pages=A120 |doi=10.1051/0004-6361/201117691 |arxiv=1201.2052 |bibcode=2012A&A...537A.120Z }}</ref>
}}
{{Stars of Libra}}
{{DEFAULTSORT:Delta Librae}} [[Category:Algol variables]] [[Category:B-type main-sequence stars]] [[Category:Eclipsing binaries]] [[Category:Stars with proper names|Zuben Elakribi]] [[Category:Libra (constellation)]] [[Category:Bayer objects|Librae, Delta]] [[Category:Durchmusterung objects|BD-07 3938]] [[Category:Flamsteed objects|Librae, 19]] [[Category:Henry Draper Catalogue objects|132742]] [[Category:Hipparcos objects|073473]] [[Category:Bright Star Catalogue objects|5586]]