Editing Beta Librae

{{short description|Star in the constellation Libra}}
{{Starbox begin
 | name = Beta Librae
}}
{{Starbox image
| image = 
     <div style="position: relative">[[File:Libra IAU.svg|250px|alt=Diagram showing star positions and boundaries of the Libra constellation and its surroundings]]
     <div style="position: absolute; left: 49.3%; top: 31.4%;">[[File:Cercle rouge 100%.svg|12px]]</div>
     </div>
| caption = The position of β Librae (circled)
}}
{{Starbox observe
 | epoch    = J2000
 | ra       = {{RA|15|17|00.41382}}<ref name=aaa474_2_653/>
 | dec      = {{DEC|−09|22|58.4919}}<ref name=aaa474_2_653/>
 | appmag_v = 2.61<ref name=scfs/>
 | constell = [[Libra (constellation)|Libra]]
}}
{{Starbox character
 | class    = B8&nbsp;V<ref name=apj736_2_89/>
 | b-v      = −0.106<ref name=apjs15_459/>
 | u-b      = −0.359<ref name=apjs15_459/>
 | variable = Suspected
|type=[[Main sequence]]}}
{{Starbox astrometry
 | radial_v = −35.2<ref name=scfs/>
 | prop_mo_ra  = −98.10<ref name=aaa474_2_653/>
 | prop_mo_dec = −19.65<ref name=aaa474_2_653/>
 | parallax = 17.62
 | p_error  = 0.16
 | parallax_footnote = <ref name=aaa474_2_653/>
 | absmag_v = −1.16<ref name=Anderson2012/>
}}
{{Starbox detail
 | mass     = {{val|3.5|+0.3|-0.2}}<ref name=apj736_2_89/>
 | radius   = 4.9<ref name=lang2006/>
 | luminosity  = 130
 | temperature = {{val|12300}}<ref name=aaa501_1_297/>
 | metal_fe    = 0.33<ref name=apj736_2_89/>
 | rotational_velocity = 250<ref name=apj573_1_359/>
 | age_myr  = {{val|80|+50|-40}}<ref name=apj736_2_89/>
}}
{{Starbox catalog
 | names = Zubeneschamali, Kiffa Australis, Lanx Borealis, β Lib, [[Flamsteed designation|27]] Librae, [[Bonner Durchmusterung|BD]]−08°3935, [[FK5]] 564, [[Henry Draper catalogue|HD]] 135742, [[Hipparcos catalogue|HIP]] 74785, [[Harvard Revised catalogue|HR]] 5685, NSV 7009, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 140430<ref name=SIMBAD/>
}}
{{Starbox reference
|Simbad=bet+Lib
}}
{{Starbox end}}

'''Beta Librae''' ('''β Librae''', abbreviated '''Beta Lib''', '''β Lib'''), formally named '''Zubeneschamali''' {{IPAc-en|z|uː|ˌ|b|ɛ|n|ɛ|ʃ|ə|ˈ|m|eɪ|l|i}},<ref name=Kunitzsch>{{cite book
 |last1=Kunitzsch |first1=Paul
 |last2=Smart |first2=Tim
 |date = 2006 |edition = 2nd rev.
 |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
 |publisher = Sky Pub |location = Cambridge, Massachusetts
 |isbn = 978-1-931559-44-7
}}</ref><ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref> is (despite its '[[beta]]' designation) the brightest [[star]] in the [[zodiac]] [[constellation]] of [[Libra (constellation)|Libra]]. From [[parallax]] measurements, its distance can be estimated as {{Convert|185|ly|pc|abbr=off|lk=on}} from the [[Sun]].<ref name=aaa474_2_653/>

The [[apparent visual magnitude]] of this star is 2.6.<ref name=scfs/> According to [[Eratosthenes]], Beta Librae was observed to be brighter than [[Antares]]. [[Ptolemy]], 350 years later, said it was as bright as Antares. The discrepancy may be due to Antares becoming brighter, but this is not known for certain. It could simply be caused by Beta Librae being a [[variable star]], showing a present-day variability of 0.03 of a magnitude.<ref name="Auk"/>

==Name==
''β Librae'' ([[Latinisation of names|Latinised]] to ''Beta Librae'') is the star's [[Bayer designation]].

It bore the traditional name ''Zubeneschamali'' {{IPAc-en|ˌ|z|uː|b|ən|ˌ|ɛ|ʃ|ə|ˈ|m|eɪ|l|i}} (less common renderings, or corruptions, are ''Zuben Eschamali'', ''Zuben el Chamali'', ''Zubenesch'', ''Zubenelg''), derived from the [[Arabic]] الزُّبَانَى الشَمَالِي (''al-zubānā al-šamāliyy'') meaning "the northern claw".<!--Note: the Auk reference has a garbled version of the Arabic.--> This name originated in a time when Libra was viewed as representing the "claws of the [[Scorpius|scorpion]]".<ref name="Auk"/> There was also ''Kiffa Borealis'', from the Arabic ''al-kiffah aš-šamāliyy'' "the northern pan (of the scales)" and the [[Latin]] equivalent ''Lanx Borealis''.<ref name=lahire1727/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN">{{citation
 | url=https://www.iau.org/science/scientific_bodies/working_groups/280/
 | title=IAU Working Group on Star Names (WGSN)
 | publisher=[[International Astronomical Union]]
 | access-date=22 May 2016 | postscript=. }}</ref> to catalogue and standardize proper names for stars. The WGSN approved the name ''Zubeneschamali'' for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>

In [[Chinese astronomy|Chinese]], {{lang|zh|氐宿}} ({{lang|zh-Latn|Dī Xiù}}), meaning ''[[Root (Chinese constellation)|Root]]'', refers to an asterism consisting of β Librae, [[Alpha Librae|α<sup>2</sup> Librae]], [[ι Librae]] and [[γ Librae]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for β Librae itself is {{lang|zh|氐宿四}} ({{lang|zh-Latn|Dī Xiù sì}}), "the Fourth Star of Root".<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>

== Properties ==
Based upon the features of its [[stellar spectrum|spectrum]], Beta Librae has a [[stellar classification]] of B8&nbsp;V,<ref name=apj736_2_89/> making it a [[B-type main-sequence star]]. It is about 130 times more luminous than the Sun and has a surface temperature of {{val|12300|fmt=commas|ul=K}},<ref name=aaa501_1_297/> double that of the Sun. This high temperature produces light with a simple spectrum, making it ideal for examining the interstellar gas and dust between Earth and the star. Like many stars of its kind, it is spinning rapidly, over 100 times faster than the Sun with a [[projected rotational velocity]] of {{nowrap|250 km·s<sup>−1</sup>}}.<ref name=apj573_1_359/> The measured [[angular diameter]] of the primary star is 0.801&nbsp;[[milliarcsecond|mas]].<ref name=aaa501_1_297/> At the estimated distance of this system, this yields a physical size of about 4.9 times the [[radius of the Sun]].<ref name=lang2006/>

This type of massive, hydrogen-fusing star often appears blue-white, and is usually stated to be white or bluish by modern observers, but earlier observers often described Beta Librae as the only greenish star visible to the naked eye.<ref name="uiuc"/> There seems to be no generally accepted explanation for why some observers see it as green.<ref name=burnham1978/> The small periodic variations in the magnitude of Beta Librae suggest the presence of a companion star which is not directly observable from Earth.<ref name="glyphweb"/> However, it is categorized as a single star.<ref name=mnras389_2_869/>

In around 200 million years, Beta Librae would have exhausted the supply of hydrogen in its core and become a [[giant star]] similar to [[Beta Herculis]], which had a similar initial mass.<ref>{{Cite web |title=kornephoros |url=http://stars.astro.illinois.edu/sow/kornephoros.html |access-date=2024-08-04 |website=stars.astro.illinois.edu}}</ref>

== See also ==
* [[List of stars in Libra]]
* [[Alpha Librae]] (Zubenelgenubi)

==References==
{{reflist|refs=

<ref name=aaa474_2_653>{{cite journal
 | title=Validation of the new Hipparcos reduction
 | last=van Leeuwen | first=F.
 | journal=Astronomy and Astrophysics
 | volume=474 | issue=2 |date=November 2007 | pages=653–664
 | doi=10.1051/0004-6361:20078357 | s2cid=18759600
 | bibcode=2007A&A...474..653V |arxiv = 0708.1752 }}</ref>

<ref name=burnham1978>{{citation | postscript=.
 | last=Burnham | first=Robert Jr. | author-link=Robert Burnham Jr.
 | title=Burnham's Celestial Handbook | volume=2
 | publisher=[[Dover Publications]] | year=1978
 | location=New York | isbn=0-486-23568-8 | page=1105
 | url=https://books.google.com/books?id=lNcbcoWiY5oC&pg=PA1105 }}</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 | page=331 | year=2012
 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
 | arxiv=1108.4971 | s2cid=119257644 | postscript=. }}</ref>

<ref name=scfs>{{citation | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | journal=Veröff. Astron. Rechen-Inst. Heidelb | volume=35 | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | page=1 | year=1999 | bibcode=1999VeARI..35....1W | postscript=. }}</ref>

<ref name=apj736_2_89>{{citation | display-authors=1 | last1=Janson | first1=Markus | last2=Bonavita | first2=Mariangela | last3=Klahr | first3=Hubert | last4=Lafrenière | first4=David | last5=Jayawardhana | first5=Ray | last6=Zinnecker | first6=Hans | title=High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood | journal=The Astrophysical Journal | volume=736 | issue=2 | page=89 |date=August 2011 | doi=10.1088/0004-637X/736/2/89 | bibcode=2011ApJ...736...89J |arxiv = 1105.2577 | s2cid=119217803 }}</ref>

<ref name=apj573_1_359>{{citation | 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 | issue=1 | pages=359–365 |date=July 2002 | doi=10.1086/340590 | bibcode=2002ApJ...573..359A | doi-access=free }}</ref>

<ref name=apjs15_459>{{citation | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=Hugo | title=A photometric investigation of the Scorpio-Centaurus association |  journal=Astrophysical Journal Supplement | volume=15 | page=459 |date=June 1968 | bibcode=1968ApJS...15..459G | doi=10.1086/190168 | doi-access=free }}</ref>

<ref name=aaa501_1_297>{{citation | display-authors=1 | last1=Zorec | first1=J. | last2=Cidale | first2=L. | last3=Arias | first3=M. L. | last4=Frémat | first4=Y. | last5=Muratore | first5=M. F. | last6=Torres | first6=A. F. | last7=Martayan | first7=C. | last8=Martayan | first8=C. | title=Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff | journal=Astronomy and Astrophysics | volume=501 | issue=1 | pages=297–320 |date=July 2009 | doi=10.1051/0004-6361/200811147 | bibcode=2009A&A...501..297Z |arxiv = 0903.5134 | s2cid=14969137 }}</ref>

<ref name=SIMBAD>{{cite simbad | title=bet Lib | accessdate=2007-01-22 }}</ref>

<ref name=lang2006>{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3 | publisher=[[Birkhäuser]] | year=2006 | isbn=3-540-29692-1 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
 & = \frac{(56.8\cdot 0.801\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
 & \approx 9.8\cdot R_{\bigodot}
\end{align}</math></ref>

<ref name=mnras389_2_869>{{cite journal | 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 }}</ref>

<ref name="uiuc">{{citation | title=Zubeneschamali | first1=James B. | last1=Kaler | publisher=[[University of Illinois]] | url=http://www.astro.uiuc.edu/~kaler/sow/zubenes.html | work=Stars | year=2006 | access-date=2006-07-03  | archive-url=https://web.archive.org/web/20060714121424/http://www.astro.uiuc.edu/~kaler/sow/zubenes.html | archive-date=2006-07-14 }}</ref>

<ref name="glyphweb">{{citation | title=Zuben Elschemali | work=The Electronic Sky | author=Mark Fisher | year=1999–2006 | url=http://www.glyphweb.com/esky/stars/zubenelschemali.html | access-date=2009-01-25 }}</ref>

<ref name=lahire1727>{{citation | url=https://archive.org/stream/tabulaeastronom00suntgoog#page/n146/mode/2up | first1=Philippe | last1=La Hire | title=Tabulae Astronomicae | year=1727| publisher=Parisiis : Apud Montalant, typographum & bibliopolam ... }}, see star table, page 13.</ref>

<ref name="Auk">{{citation | title=LIBRA – A Balanced View (page 7 of PDF) | work=Auckland Astronomical Society | url=http://www.astronomy.org.nz/Documents/Journal/journal_200606.pdf | author=AAS | year=2006 | access-date=2009-01-25 | archive-date=2012-02-12 | archive-url=https://web.archive.org/web/20120212212303/http://www.astronomy.org.nz/Documents/Journal/journal_200606.pdf  }}</ref>

}}

==External links==
*{{citation | url=http://www.icoproject.org/star.html | title=Arabic Star Names | work=Islamic Crescents' Observation Project | first1=Moh'd | last1=Odeh | year=1998–2006 | access-date=2006-07-03 | archive-date=2008-02-02 | archive-url=https://web.archive.org/web/20080202163504/http://www.icoproject.org/star.html  }} – Find more Arabic Star Names and their meanings.
*{{WikiSky|Beta Librae}}
{{Sky|15|17|00.41382|-|09|22|58.4919|160.038411}}
{{Stars of Libra}}

{{DEFAULTSORT:Beta Librae}}
[[Category:Bayer objects|Librae, Beta]]
[[Category:B-type main-sequence stars]]
[[Category:Libra (constellation)]]
[[Category:Stars with proper names|Zubeneschamali]]
[[Category:Flamsteed objects|Librae, 27]]
[[Category:Hipparcos objects|074785]]
[[Category:Suspected variables]]
[[Category:Bright Star Catalogue objects|5685]]
[[Category:Henry Draper Catalogue objects|135742]]
[[Category:Durchmusterung objects]]